Patent ID: 8061384

Claim:
A pressure controller comprising: a housing in a hollow shape having a plurality of ports; a drive valve freely movably supported in the housing; an energizing unit communicatively connecting or blocking the plurality of ports by energizing the drive valve in a direction in which the drive valve is caused to approach a valve seat or separate from the valve seat; a solenoid controlling a differential pressure by communicatively connecting or blocking the plurality of ports with a movement of the drive valve by means of an electromagnetic force against an energizing force of the energizing unit; an external piston capable of pressing the drive valve against the energizing force of the energizing unit from outside the housing; and a pressure control unit performing pressure control so that a control pressure acting on the external piston from a side of the drive valve is equal to or greater than an external pressure acting from outside, wherein the drive valve includes an axial communicating path that communicates the control pressure acting on the external piston from the side of the drive valve.