Disclosed is an electric driver which is capable of freely controlling the rotational speed of a motor or a bit. The electric driver comprises a transmission mechanism provided between a drive shaft of the motor and the bit, and the transmission mechanism includes a clutch device operated to release the bit from a driven connection with the drive shaft when a transmission torque from the drive shaft to the bit exceeds a predetermined value. The clutch device has an elastic member and the predetermined torque value is adjustable by means of the elastic member.