Valve

A valve comprising:

• a valve body having an inflow port and an outflow port for a fluid, and a valve chamber;
• a valve seat provided in the valve chamber and having a seat surface that is an open end of a flow passage communicating with the inflow port;
• a columnar stem connected to an actuator and including, at a tip end of the stem, a valve element configured to abut against and move away from the seat surface due to an operation of the actuator;
• a seal member provided in a seal space that communicates with the outside from the valve chamber, fitted onto the stem, and configured to prevent the fluid from leaking from the valve chamber;
• and
• a seal pressing member configured to press and fix the seal member to a valve chamber side, wherein
• the seal member is implemented by attaching an inner seal member and an outer seal member to a continuous cylindrical seal holding member, and the inner seal member is on a side of the actuator, and
• the stem is formed with, in an assembled state, a pressure release portion that is nearer to the seal pressing member than is a position at which the seal member is in sliding contact and the pressure release portion is formed at the position that overlaps the inner seal member when the seal pressing member is loosened.