A jack with switch comprises a body that has a plug insertion hole and a switch chamber which is adjacent to the plug insertion hole. The plug insertion hole and the switch chamber communicate with one another. The switch chamber contains a separator partly projecting into the plug insertion hole, a movable contactor piece, and a stationary contactor piece. When a plug is inserted into the plug insertion hole, the separator is transversely displaced to space the movable contactor piece apart from the stationary contactor piece. When the separator is displaced or moved by a predetermined extent, the separator hits a projected wall portion formed in the switch chamber in order to restrict further displacement of the separator. Even if the plug is wrenched in the jack, the movable contactor piece is prevented from excessive displacement.