PROBLEM TO BE SOLVED: To suppress a projection amount from a wheel to an axial direction outer side.SOLUTION: A drive unit 20A comprises: a motor 21 with a speed reducer for rotating an output member 237； a wheel 13r which is so supported as to be rotatable relatively to the output member 237； and a clutch mechanism 300 which can perform changeover between an assist state that a turning force of the output member 237 is transmitted to the wheel 13r and a free state that transmission of the turning force of the output member 237 to the wheel 13r is blocked. The clutch mechanism 300 comprises a drive plate 240 which rotates integrally to the output member 237 on an inner peripheral side of the wheel 13r, and a shaft body 321 which moves in a radial direction of the wheel 13r thereby performing engagement and disengagement between the drive plate 240 and the wheel 13r.SELECTED DRAWING: Figure 3【課題】車輪から軸方向外側への突出量を抑える。【解決手段】駆動ユニット２０Ａは、出力部材２３７を回転させる減速機付モータ２１と、出力部材２３７に対して相対回転可能に支持された車輪１３ｒと、車輪１３ｒに出力部材２３７の回転力を伝達するアシスト状態と、車輪１３ｒへの出力部材２３７の回転力の伝達を遮断するフリー状態とに切替可能なクラッチ機構３００と、を備え、クラッチ機構３００は、車輪１３ｒの内周側で出力部材２３７と一体に回転する駆動プレート２４０と、車輪１３ｒの径方向に移動することで駆動プレート２４０と車輪１３ｒとを係脱するシャフト本体３２１と、を備える。【選択図】図３
