PURPOSE: To allow a lever to be rocked by both the cam of an operating member and the roller of the lever, allow the lever to be thereby sucked in by the push-rod of a solenoid, so that a hydraulic pilot valve is held by itself in a hydraulic pressure supply condition, and meanwhile also allow selfholding to be simply released with the solenoid de-magnetized.

CONSTITUTION: When an operating member 25 is rocked, and a spool 15 is concurrently impulsively moved downward with a piston 12 pushed, an inlet port 13 is communicated with an outlet port 14. In this case, a cam 26 provided for the operating member 25 is revolved, a roller 27 comes in contact with a notch section 39, and the roller runs on the notch section 39 thereafter, so that a lever 28 is rocked upward against a spring 30. And a push rod 36 is raised up via a contact 31 and a link mechanism 37 as the end section 28a of the lever 28 is raised up, so that the push rod is sucked in a solenoid main body 35. Namely, a valve is held by itself in a hydraulic pressure oil supply condition. Meanwhile, when the solenoid main body 35 is de-energized, the operating member 25 is automatically returned to an original position together with the cam 26 by returning force exerting a pressure reducing section 11.