A handy electric nailing gun includes a firing pin, a firing spring for pushing the firing pin to drive nails into workpiece, an output gear rotatable by a motor through a transmission gear set to retract the firing pin during the first half run of each rotation cycle and to release the firing pin during the second half run of each rotation cycle, and three power switches electrically connected in series between the motor and the power source (AC adapter/rechargeable battery) for operation by the user to control the operation of the motor.