PURPOSE: To provide a pressure oil supply/discharge device for a hydraulic shaft coupling which suppress leakage of pressure oil to minimum when the pressure oil is supplied to the hydraulic shaft joint and sealed by a check valve mechanism, and opens the check valve mechanism in a contraflow direction with facility and certainly.

CONSTITUTION: Pressure oil supply/discharges devices 11, 12 are operated for supplying and discharging pressure oil to a hydraulic shaft coupling which is connected by sealing the supplied pressure oil and disconnected by discharging the sealed pressure oil. There are provided a valve body 35 formed a valve seat 37 having a primary port 38 to be connected to a pressure oil supply device 60, a poppet 41 holding a ball 40 pressed against the valve seat 37 and main bodies 30, 31, 32 holding the valve body 35 and housing the poppet 41 in a movable manner in the pressurizing direction, and commonly having a secondary port 49. A belleville spring 44 presses the poppet 41 against the valve seat 37. A shaft member 45 is connected to the poppet 41 and has a tapered portion 46 perpendicular to the pressing direction. A wedge member 54 is operated for pressing the tapered portion in an opposite direction to the pressing direction.