To incorporate a drive motor in a front wheel itself to simplify the structure, inexpensively manufacture bicycles, and improve even an existing bicycle into a motor assisting bicycle simply by changing its front wheel.

With this bicycle, a drive motor 27, a battery for supplying power to the drive motor, and a control circuit 31 for controlling the battery are provided. In this case, a drive gear 28 to be connected to the drive motor 27 is provided in a fixed side housing 20, and a driven gear 29 with which the drive gear 28 is to be engaged is provided in a movable side housing 21 to form a wheel-motor consisting of a planetary gear mechanism. The fixed side housing 20 is fixed to a fork of a front wheel 4, and the movable side housing 21 is provided inside a hub 5 of the front wheel 4.