An output power transmission device has a transmission plate and a C-ring. The transmission plate is attached to a wheel gear in an axial direction of the wheel gear such that the transmission plate directly engages with the wheel gear in a rotation direction. The transmission plate functions as a transmission member for transmitting rotation of the wheel gear to an output shaft. The C-ring is provided at a position where the C-ring sandwiches the transmission plate with the wheel gear in the axial direction. The C-ring functions as a restriction section for restricting movement of the transmission plate in the axial direction opposite from the wheel gear side. An elastic claw section as a pressing member is formed on the wheel gear. The elastic claw section presses the transmission plate against the C-ring in the axial direction.