A flow passage unit of a switching valve includes an energy-saving valve mechanism provided in a second flow passage of a flow passage body. The energy-saving valve mechanism has a movable body including a piston section and a valve member, and an elastic member that biases the movable body elastically. At a time that compressed air is supplied to the second flow passage, when a force that acts on the piston section based on the pressure of a first flow passage becomes smaller than a biasing force of the elastic member, due to the biasing force of the elastic member, the movable body is moved to a valve-closed position for blocking the second flow passage.