Abstract: A locking and unlocking device comprises an electromagnetic actuator which pulls in or pushes out an output rod thereof, a movement direction changing mechanism alternating the direction of its rotational movement with each of said pulling-in and pushing-out operations of said electromagnetic actuator, a lock lever rocking alternately in opposite directions with each of said pulling-in and pushing-out operations of said electromagnetic actuator, a main body of a locking apparatus linked with said lock lever and effecting locking and unlocking operations, position detector switch means linked with a moving part of said main body of said locking apparatus thereby being caused to change over with each of said locking and unlocking operations to control energization of said electromagnetic actuator, and operation switch means for initiating said locking and unlocking operations, respectively. The changing-over of said position detector switch means determines which operation switch means is subsequently operable.