The inflow of an external fluid into a mounting hole of a displacement control valve can be prevented, and accumulated gas in the mounting hole due to the permeation leakage of high-pressure gas can be discharged to the outside. A displacement control valve 1 inserted and fitted in a mounting hole 3 provided in a casing of a device controlled in displacement includes a sealing lip 46. The sealing lip 46 is fitted in a fitting section 41 at an outer peripheral portion of the displacement control valve 1 on a side close to an entrance of the mounting hole 3. The sealing lip 46 has a lip portion 46b abutting on an inner peripheral surface of the mounting hole 3.