Patent ID: 7143956

Claim:
A suck back valve comprising: a main body section which is provided with a fluid passage for making communication between a first port and a second port; an ON/OFF valve mechanism which opens/closes said fluid passage by displacing a valve member together with a first piston under an action of a pressure fluid when said pressure fluid is supplied into a first cylinder chamber via a first pilot port; and a suck back mechanism which has a deformable suction member with a flow chamber formed therein so that fluid contained in said fluid passage is sucked by displacing said suction member together with a second piston under an action of said pressure fluid when said pressure fluid is supplied to a second cylinder chamber via a second pilot port, wherein said ON/OFF valve mechanism and said suck back mechanism are assembled coaxially and integrally, and wherein a through-hole, which extends in an axial direction, is formed in said first piston, and a part of said second piston is internally installed in said through-hole.