An in-wheel motor system having a flexible coupling for transmitting the drive torque of a motor to a wheel. The flexible coupling 10 simple in structure and easily assembled comprises a motor-side plate (11A) mounted to the rotating side case of the motor, a wheel-side plate (11C) mounted to the wheel or a hub, an intermediate plate (11B) disposed between these two plates (11A) and (11C), a first rubber member (12a) of generally rectangular shape in plan view which connects the motor-side plate (11A) to the intermediate plate (11B) in such a manner that they can move relative to each other in a direction (direction B) orthogonal to their connection direction (direction A), and a second rubber member (12b) formed in the same manner as the first rubber member (12a) which connects the intermediate plate (11B) to the wheel side plate (11C) in such a manner that they can move relative to each other in the direction A orthogonal to the direction B.