diff --git a/README.md b/README.md
index 61ec7e4b..a654e33f 100644
--- a/README.md
+++ b/README.md
@@ -132,7 +132,7 @@ for (let i = 0; i < n; i++) {
 | feature selection | Mutual information, Ridge, Lasso, Elastic net, Decision tree, NCA |
 | transformation | Box-Cox, Yeo-Johnson |
 | density estimation | Histogram, Average shifted histogram, Polynomial histogram, Maximum likelihood, Kernel density estimation, k-nearest neighbor, Naive Bayes, GMM, HMM |
-| generate | MH, Slice sampling, GMM, GBRBM, HMM, VAE, GAN, NICE |
+| generate | MH, Slice sampling, GMM, GBRBM, HMM, VAE, GAN, NICE, Diffusion |
 | smoothing | (Linear weighted / Triangular / Cumulative) Moving average, Exponential average, Moving median, KZ filter, Savitzky Golay filter, Hampel filter, Kalman filter, Particle filter, Lowpass filter, Bessel filter, Butterworth filter, Chebyshev filter, Elliptic filter |
 | timeseries prediction | Holt winters, AR, ARMA, SDAR, VAR, Kalman filter, MLP, RNN |
 | change point detection | Cumulative sum, k-nearest neighbor, LOF, COF, SST, KLIEP, LSIF, uLSIF, LSDD, HMM, Markov switching |
diff --git a/js/model_selector.js b/js/model_selector.js
index 2ecf558c..4af8382b 100644
--- a/js/model_selector.js
+++ b/js/model_selector.js
@@ -484,6 +484,7 @@ const AIMethods = [
 			{ value: 'vae', title: 'VAE' },
 			{ value: 'gan', title: 'GAN' },
 			{ value: 'nice', title: 'NICE' },
+			{ value: 'diffusion_model', title: 'Diffusion Model' },
 		],
 	},
 	{
diff --git a/js/view/diffusion_model.js b/js/view/diffusion_model.js
new file mode 100644
index 00000000..a8c8b155
--- /dev/null
+++ b/js/view/diffusion_model.js
@@ -0,0 +1,72 @@
+import Controller from '../controller.js'
+import { BaseWorker } from '../utils.js'
+
+class DiffusionModelWorker extends BaseWorker {
+	constructor() {
+		super('js/view/worker/model_worker.js', { type: 'module' })
+	}
+
+	initialize(timesteps) {
+		return this._postMessage({ name: 'diffusion_model', method: 'constructor', arguments: [timesteps] })
+	}
+
+	epoch() {
+		return this._postMessage({ name: 'diffusion_model', method: 'epoch' }).then(r => r.data)
+	}
+
+	fit(train_x, iteration, rate, batch) {
+		return this._postMessage({
+			name: 'diffusion_model',
+			method: 'fit',
+			arguments: [train_x, iteration, rate, batch],
+		}).then(r => r.data)
+	}
+
+	generate(n) {
+		return this._postMessage({ name: 'diffusion_model', method: 'generate', arguments: [n] }).then(r => r.data)
+	}
+}
+
+export default function (platform) {
+	platform.setting.ml.usage =
+		'Click and add data point. Next, click "Initialize". Finally, click "Fit" button repeatedly.'
+	const controller = new Controller(platform)
+	const model = new DiffusionModelWorker()
+	let epoch = 0
+
+	const fitModel = async () => {
+		if (platform.datas.length === 0) {
+			return
+		}
+		const tx = platform.trainInput
+		const loss = await model.fit(tx, +iteration.value, rate.value, batch.value)
+		epoch = await model.epoch()
+		platform.plotLoss(loss[0])
+		const gen_data = await model.generate(tx.length)
+		platform.trainResult = gen_data
+	}
+
+	const genValues = async () => {
+		const ty = platform.trainOutput
+		genBtn.element.disabled = true
+		const gen_data = await model.generate(platform.trainInput.length, ty)
+		genBtn.element.disabled = false
+		console.log(gen_data)
+		platform.trainResult = gen_data
+	}
+
+	const slbConf = controller.stepLoopButtons().init(done => {
+		model.initialize(100).then(done)
+		platform.init()
+	})
+	const iteration = controller.select({ label: ' Iteration ', values: [1, 10, 100, 1000, 10000] })
+	iteration.value = 10
+	const rate = controller.input.number({ label: 'Learning rate ', min: 0, max: 100, step: 0.01, value: 0.01 })
+	const batch = controller.input.number({ label: ' Batch size ', min: 1, max: 100, value: 10 })
+	slbConf.step(fitModel).epoch(() => epoch)
+	const genBtn = controller.input.button('Generate').on('click', genValues)
+
+	return () => {
+		model.terminate()
+	}
+}
diff --git a/lib/model/diffusion_model.js b/lib/model/diffusion_model.js
new file mode 100644
index 00000000..d852ac2f
--- /dev/null
+++ b/lib/model/diffusion_model.js
@@ -0,0 +1,176 @@
+import Matrix from '../util/matrix.js'
+import Tensor from '../util/tensor.js'
+import NeuralNetwork from './neuralnetwork.js'
+
+/**
+ * Diffusion model network
+ */
+export default class DiffusionModel {
+	// https://qiita.com/pocokhc/items/5a015ee5b527a357dd67
+	/**
+	 * @param {number} timesteps Number of timestep
+	 * @param {LayerObject[]} [layers] Layers
+	 */
+	constructor(timesteps, layers) {
+		this._timesteps = timesteps
+		this._ulayers = layers
+		this._peDims = 32
+
+		this._model = null
+		this._epoch = 0
+
+		const betaStart = 0.0001
+		const betaEnd = 0.02
+		const betaStep = (betaEnd - betaStart) / (this._timesteps - 1)
+		this._beta = [betaStart]
+		for (let t = 1; t < this._timesteps - 1; t++) {
+			this._beta[t] = betaStart + betaStep * t
+		}
+		this._beta.push(betaEnd)
+		this._alpha = [1 - this._beta[0]]
+		this._alphaCumprod = [this._alpha[0]]
+		for (let t = 1; t < this._beta.length; t++) {
+			this._alpha[t] = 1 - this._beta[t]
+			this._alphaCumprod[t] = this._alphaCumprod[t - 1] * this._alpha[t]
+		}
+	}
+
+	/**
+	 * Epoch
+	 * @type {number}
+	 */
+	get epoch() {
+		return this._epoch
+	}
+
+	_addNoise(x, t) {
+		const at = this._alphaCumprod[t]
+		const sqrtat = Math.sqrt(at)
+		const sqrt1at = Math.sqrt(1 - at)
+		const noize = Tensor.randn(x.sizes)
+		const xNoised = x.copy()
+		xNoised.broadcastOperate(noize, (a, b) => sqrtat * a + sqrt1at * b)
+		return [xNoised, noize]
+	}
+
+	_build() {
+		if (this._dataShape.length === 1) {
+			this._layers = [
+				{ type: 'input', name: 'x' },
+				{ type: 'input', name: 'position_encoding' },
+				{ type: 'full', out_size: this._peDims, l2_decay: 0.001, activation: 'gelu', name: 'pe' },
+				{ type: 'concat', input: ['x', 'pe'], axis: 1 },
+			]
+			if (this._ulayers) {
+				this._layers.push(...this._ulayers)
+			} else {
+				this._layers.push(
+					{ type: 'full', out_size: 32, l2_decay: 0.001, name: 'c1', activation: 'tanh' },
+					{ type: 'full', out_size: 16, l2_decay: 0.001, activation: 'tanh' },
+					{ type: 'full', out_size: 32, l2_decay: 0.001, name: 'u1', activation: 'tanh' },
+					{ type: 'concat', input: ['u1', 'c1'], axis: 1 },
+					{ type: 'full', out_size: 32, l2_decay: 0.001, activation: 'tanh' }
+				)
+			}
+			this._layers.push({ type: 'full', out_size: this._dataShape[0], l2_decay: 0.001 }, { type: 'output' })
+		} else {
+			const dim = this._dataShape.length
+			this._layers = [
+				{ type: 'input', name: 'x' },
+				{ type: 'input', name: 'position_encoding' },
+				{ type: 'full', out_size: this._peDims, l2_decay: 0.001, activation: 'gelu' },
+				{ type: 'reshape', size: [...Array(dim - 1).fill(1), this._peDims] },
+				{ type: 'up_sampling', size: this._dataShape.slice(0, dim - 1), name: 'pe' },
+				{ type: 'concat', input: ['x', 'pe'], axis: dim },
+			]
+			if (this._ulayers) {
+				this._layers.push(...this._ulayers)
+			} else {
+				this._layers.push(
+					{
+						type: 'conv',
+						kernel: 3,
+						channel: 16,
+						padding: 1,
+						l2_decay: 0.001,
+						name: 'c1',
+						activation: 'relu',
+					},
+					{ type: 'max_pool', kernel: 2 },
+					{ type: 'conv', kernel: 3, channel: 32, padding: 1, l2_decay: 0.001, activation: 'relu' },
+					{ type: 'up_sampling', size: 2, name: 'u1' },
+					{ type: 'concat', input: ['u1', 'c1'], axis: dim },
+					{ type: 'conv', kernel: 3, channel: 16, padding: 1, l2_decay: 0.001, activation: 'relu' }
+				)
+			}
+			this._layers.push(
+				{ type: 'conv', kernel: 1, channel: this._dataShape[dim - 1], l2_decay: 0.001 },
+				{ type: 'output' }
+			)
+		}
+
+		return NeuralNetwork.fromObject(this._layers, 'mse', 'adam')
+	}
+
+	_positionEncoding(t, embdims) {
+		const rates = Array.from({ length: embdims }, (_, i) => t / 10000 ** (2 * Math.floor(i / 2)) / embdims)
+		const pe = rates.map((v, i) => (i % 2 === 0 ? Math.sin(v) : Math.cos(v)))
+		return new Matrix(1, embdims, pe)
+	}
+
+	/**
+	 * Fit model.
+	 * @param {Array<Array<number>>} train_x Training data
+	 * @param {number} iteration Iteration count
+	 * @param {number} rate Learning rate
+	 * @param {number} batch Batch size
+	 * @returns {{labeledLoss: number, unlabeledLoss: number}} Loss value
+	 */
+	fit(train_x, iteration, rate, batch) {
+		const x = Tensor.fromArray(train_x)
+		this._dataShape = x.sizes.slice(1)
+		if (!this._model) {
+			this._model = this._build()
+		}
+		let loss = null
+		for (let i = 0; i < iteration; i++) {
+			const t = Math.floor(Math.random() * this._timesteps)
+			const pe = this._positionEncoding(t, this._peDims)
+			pe.repeat(x.sizes[0], 0)
+			const [noised_x, noise] = this._addNoise(x, t)
+
+			loss = this._model.fit({ x: noised_x, position_encoding: pe }, Tensor.fromArray(noise), 1, rate, batch)
+		}
+		this._epoch += iteration
+		return loss
+	}
+
+	/**
+	 * Returns generated data from the model.
+	 * @param {number} n Number of generated data
+	 * @returns {Array<Array<number>>} Generated values
+	 */
+	generate(n) {
+		const ds = this._dataShape.concat()
+		const samples = Tensor.randn([n, ...ds])
+		for (let t = this._timesteps - 1; t >= 0; t--) {
+			const pe = this._positionEncoding(t, this._peDims)
+			pe.repeat(n, 0)
+
+			const pred = this._model.calc({ x: samples, position_encoding: pe })
+
+			samples.broadcastOperate(
+				pred,
+				(a, b) =>
+					(1 / Math.sqrt(this._alpha[t])) * (a - (b * this._beta[t]) / Math.sqrt(1 - this._alphaCumprod[t]))
+			)
+			if (t > 0) {
+				const s2 = ((1 - this._alphaCumprod[t - 1]) / (1 - this._alphaCumprod[t])) * this._beta[t]
+				const noise = Tensor.randn(samples.sizes, 0, s2)
+				samples.broadcastOperate(noise, (a, b) => a + b)
+			}
+		}
+
+		return samples.toArray()
+	}
+}
diff --git a/lib/model/nns/layer/full.js b/lib/model/nns/layer/full.js
index c43619a2..d1346e47 100644
--- a/lib/model/nns/layer/full.js
+++ b/lib/model/nns/layer/full.js
@@ -93,15 +93,20 @@ export default class FullyConnected extends Layer {
 			i = this._i.copy()
 			i.reshape(-1, this._w.rows)
 			i = i.toMatrix()
+		} else if (!(this._i instanceof Matrix)) {
+			i = i.toMatrix()
 		}
 		let b = bo
 		if (b.dimension !== 2) {
 			b = bo.copy()
 			b.reshape(-1, this._w.cols)
 			b = b.toMatrix()
+		} else if (!(b instanceof Matrix)) {
+			b = b.toMatrix()
 		}
+		const n = this._i.sizes[0]
 		this._dw = i.tDot(b)
-		this._dw.div(this._i.rows)
+		this._dw.div(n)
 		if (this._l2_decay > 0 || this._l1_decay > 0) {
 			for (let i = 0; i < this._dw.rows; i++) {
 				for (let j = 0; j < this._dw.cols; j++) {
@@ -111,7 +116,7 @@ export default class FullyConnected extends Layer {
 			}
 		}
 		this._db = b.sum(0)
-		this._db.div(this._i.rows)
+		this._db.div(n)
 
 		this._bi = bo.dot(this._w.t)
 		if (this._wname || this._bname) {
diff --git a/lib/util/matrix.js b/lib/util/matrix.js
index 95f34b73..a7c5e594 100644
--- a/lib/util/matrix.js
+++ b/lib/util/matrix.js
@@ -461,6 +461,21 @@ export default class Matrix {
 		return s + ']'
 	}
 
+	_to_position(...i) {
+		let p = 0
+		for (let d = 0; d < this.dimension; d++) {
+			if (i[d] < 0 || this._size[d] <= i[d]) {
+				throw new MatrixException('Index out of bounds.')
+			}
+			p = p * this._size[d] + i[d]
+		}
+		return p
+	}
+
+	_to_index(p) {
+		return [Math.floor(p / this._size[1]), p % this._size[1]]
+	}
+
 	/**
 	 * Returns a copy of this matrix.
 	 * @param {Matrix<T>} [dst] Destination matrix
diff --git a/tests/gui/view/diffusion_model.test.js b/tests/gui/view/diffusion_model.test.js
new file mode 100644
index 00000000..514a5072
--- /dev/null
+++ b/tests/gui/view/diffusion_model.test.js
@@ -0,0 +1,52 @@
+import { getPage } from '../helper/browser'
+
+describe('generate', () => {
+	/** @type {Awaited<ReturnType<getPage>>} */
+	let page
+	beforeEach(async () => {
+		page = await getPage()
+		const clusters = page.locator('#data_menu input[name=n]')
+		await clusters.fill('1')
+		const resetDataButton = page.locator('#data_menu input[value=Reset]')
+		await resetDataButton.dispatchEvent('click')
+		const taskSelectBox = page.locator('#ml_selector dl:first-child dd:nth-child(5) select')
+		await taskSelectBox.selectOption('GR')
+		const modelSelectBox = page.locator('#ml_selector .model_selection #mlDisp')
+		await modelSelectBox.selectOption('diffusion_model')
+	})
+
+	afterEach(async () => {
+		await page?.close()
+	})
+
+	test('initialize', async () => {
+		const methodMenu = page.locator('#ml_selector #method_menu')
+		const buttons = methodMenu.locator('.buttons')
+
+		const iteration = buttons.locator('select:nth-of-type(1)')
+		await expect(iteration.inputValue()).resolves.toBe('10')
+		const rate = buttons.locator('input:nth-of-type(2)')
+		await expect(rate.inputValue()).resolves.toBe('0.01')
+		const batch = buttons.locator('input:nth-of-type(3)')
+		await expect(batch.inputValue()).resolves.toBe('10')
+	})
+
+	test('learn', async () => {
+		const methodMenu = page.locator('#ml_selector #method_menu')
+		const buttons = methodMenu.locator('.buttons')
+
+		const epoch = buttons.locator('[name=epoch]')
+		await expect(epoch.textContent()).resolves.toBe('0')
+		const methodFooter = page.locator('#method_footer', { state: 'attached' })
+		await expect(methodFooter.textContent()).resolves.toBe('')
+
+		const initButton = buttons.locator('input[value=Initialize]')
+		await initButton.dispatchEvent('click')
+		const stepButton = buttons.locator('input[value=Step]:enabled')
+		await stepButton.dispatchEvent('click')
+		await buttons.locator('input[value=Step]:enabled').waitFor()
+
+		await expect(epoch.textContent()).resolves.toBe('10')
+		await expect(methodFooter.textContent()).resolves.toMatch(/^loss/)
+	})
+})
diff --git a/tests/lib/model/diffusion_model.test.js b/tests/lib/model/diffusion_model.test.js
new file mode 100644
index 00000000..b51e51fd
--- /dev/null
+++ b/tests/lib/model/diffusion_model.test.js
@@ -0,0 +1,72 @@
+import { jest } from '@jest/globals'
+jest.retryTimes(3)
+
+import Matrix from '../../../lib/util/matrix.js'
+import Tensor from '../../../lib/util/tensor.js'
+import DiffusionModel from '../../../lib/model/diffusion_model.js'
+
+describe('sample', () => {
+	test('2d custom layers', async () => {
+		const model = new DiffusionModel(100, [
+			{ type: 'full', out_size: 8, l2_decay: 0.001, activation: 'tanh' },
+			{ type: 'full', out_size: 4, l2_decay: 0.001, activation: 'tanh' },
+			{ type: 'full', out_size: 8, l2_decay: 0.001, activation: 'tanh' },
+		])
+		const x = Matrix.randn(1000, 2, 2, 0.1).toArray()
+		for (let i = 0; i < 10; i++) {
+			const loss = model.fit(x, 10, 0.01, 10)
+			expect(model.epoch).toBe(10 * (i + 1))
+			const s = Matrix.fromArray(model.generate(100))
+			const curMean = s.mean()
+			const curStd = s.std()
+			if (loss[0] < 1 && Math.abs(curMean - 2) < 0.5 && curStd < 0.5) {
+				break
+			}
+		}
+
+		const s = Matrix.fromArray(model.generate(100))
+		expect(s.mean()).toBeCloseTo(2, 0)
+	})
+
+	test('2d default layers', async () => {
+		const model = new DiffusionModel(10)
+		const x = Matrix.randn(5, 2, 2, 0.1).toArray()
+		for (let i = 0; i < 1; i++) {
+			const loss = model.fit(x, 2, 0.01, 10)
+			expect(loss[0]).not.toBeNaN()
+			expect(model.epoch).toBe(2 * (i + 1))
+		}
+
+		const s = Matrix.fromArray(model.generate(100))
+		expect(s.mean()).not.toBeNaN()
+	})
+
+	test('3d default layers', async () => {
+		const model = new DiffusionModel(10)
+		const x = Tensor.randn([5, 4, 2], 2, 0.1).toArray()
+		for (let i = 0; i < 2; i++) {
+			const loss = model.fit(x, 1, 0.01, 10)
+			expect(loss[0]).not.toBeNaN()
+			expect(model.epoch).toBe(i + 1)
+		}
+
+		const s = Tensor.fromArray(model.generate(10))
+		expect(s.reduce((s, v) => s + v, 0) / s.length).not.toBeNaN()
+	})
+
+	test('3d custom layers', async () => {
+		const model = new DiffusionModel(10, [
+			{ type: 'conv', kernel: 3, channel: 4, padding: 1, l2_decay: 0.001, activation: 'relu' },
+			{ type: 'conv', kernel: 3, channel: 4, padding: 1, l2_decay: 0.001, activation: 'relu' },
+		])
+		const x = Tensor.randn([5, 4, 2], 2, 0.1).toArray()
+		for (let i = 0; i < 2; i++) {
+			const loss = model.fit(x, 1, 0.01, 10)
+			expect(loss[0]).not.toBeNaN()
+			expect(model.epoch).toBe(i + 1)
+		}
+
+		const s = Tensor.fromArray(model.generate(10))
+		expect(s.reduce((s, v) => s + v, 0) / s.length).not.toBeNaN()
+	})
+})
diff --git a/tests/lib/model/nns/layer/full.test.js b/tests/lib/model/nns/layer/full.test.js
index 2f99b2d0..63494937 100644
--- a/tests/lib/model/nns/layer/full.test.js
+++ b/tests/lib/model/nns/layer/full.test.js
@@ -94,6 +94,17 @@ describe('layer', () => {
 			const bi = layer.grad(bo)
 			expect(bi.sizes).toEqual([15, 10, 7])
 		})
+
+		test('2d tensor', () => {
+			const layer = new FullLayer({ out_size: 4 })
+
+			const x = Tensor.randn([10, 7])
+			layer.calc(x)
+
+			const bo = Tensor.ones(10, 4)
+			const bi = layer.grad(bo)
+			expect(bi.sizes).toEqual([10, 7])
+		})
 	})
 
 	test('toObject', () => {
diff --git a/tests/lib/util/matrix.test.js b/tests/lib/util/matrix.test.js
index 588ec4ee..dc8f57b8 100644
--- a/tests/lib/util/matrix.test.js
+++ b/tests/lib/util/matrix.test.js
@@ -591,6 +591,46 @@ describe('Matrix', () => {
 		expect(str).toEqual('[[1, 2, 3],\n [4, 5, 6]]')
 	})
 
+	describe('_to_position', () => {
+		test.each([
+			[[1, 1], [0, 0], 0],
+			[[2, 3], [1, 1], 4],
+		])('size:%p, index:%p', (size, idx, pos) => {
+			const mat = new Matrix(size)
+			const p = mat._to_position(...idx)
+			expect(p).toBe(pos)
+		})
+
+		test.each([
+			[
+				[1, 1],
+				[1, 1],
+			],
+			[
+				[2, 3],
+				[2, 2],
+			],
+			[
+				[3, 2],
+				[2, 2],
+			],
+		])('size:%p, fail[%p]', (size, idx) => {
+			const mat = new Matrix(size)
+			expect(() => mat._to_position(...idx)).toThrow('Index out of bounds.')
+		})
+	})
+
+	describe('_to_index', () => {
+		test.each([
+			[[1, 1], 0, [0, 0]],
+			[[2, 3], 4, [1, 1]],
+		])('size:%p, pos:%p', (size, pos, idx) => {
+			const mat = new Matrix(size)
+			const p = mat._to_index(pos)
+			expect(p).toEqual(idx)
+		})
+	})
+
 	describe('copy', () => {
 		test('default', () => {
 			const org = Matrix.randn(2, 3)