A motor-driven electric timer consists of a motor, a reduction gear assembly for reducing a rotational speed from the motor to a predetermined speed, an externally actuatable slider having at one side wall thereof a rack, a clutch mechanism consisting of a pinion gear driven by the reduction gear assembly for driving the rack and a spring wire disengageably biasing the pinion gear for engagement with the rack, a switching lever member following a side wall of the slider, a contact member actuated by the switching lever member, and a flat-shaped housing enclosing the timer.