A motor and pedal driven bicycle providing a motor driving unit (101) for giving a driving power to a wheel in which the motor driving unit includes a disc-like casing (105,106) having a space formed therein and dividable into two portions, a wheel driving motor powered by a battery (102), and a speed reducer coupled to the motor to reduce a revolution speed of the motor; the casing is composed of a fixed portion (105) secured to a hub spindle (107) of the wheel and a rotatable portion (106) provided on a hub shell mounted on said hub spindle to be rotatable along with said hub shell; and either the motor or both the motor and the speed reducer are provided on the inside of the fixed portion of the casing. <IMAGE>
