Abstract: A supply-discharge valve member (30) inserted into a valve casing (29) can be pushed downward by pressure fluid of an actuation chamber (35). A restriction passage (G) is constituted by a fitting clearance between a valve bore (61) and an opening-closing valve member (62) provided in the valve casing (29). The pressure fluid supplied to the chamber (35) is quickly discharged to an atmosphere side through the restriction passage (G) when an amount of the supplied fluid is extremely a little. When the supplied amount increases, since a flowing resistance of the restriction passage (G) increases and the pressure within the chamber (35) is increased, a closing valve surface (69) of the opening-closing valve member (62) is brought into contact with a valve seat (70) for closing by that pressure to prevent the pressure fluid from being discharged.