An electric swing mechanism includes a battery powered solenoid which exerts a motive force on a swinging infant seat. The solenoid is activated by the linear reciprocation of a specially designed actuator past a microswitch, so that the switch is closed and the solenoid activated in only one direction of the stroke. The mechanism's linkage system is designed to contact the swinging infant seat during only half of the seat's swinging cycle, and is mechanically isolated from the seat during the other half of its cycle.