An electric assisted bicycle of simple structure is provided which is superior in the stability, reliability, and certainty of operation, and is provided with an electric power regenerative function and a brake assist function. A pedal force transmitted from a crank shaft is transmitted to an axle shaft via first transmission means, and the output of a motor as an assistant motive power is transmitted to the axle shaft via a clutch unit, which can switch a lock direction in conjunction with brake operation by a cyclist, and second transmission means.