PURPOSE: To prevent reverse turning of a rotor upon compressor stopping by providing a valve mechanism and a throttle unit in an oil passage which connects an oil sump part to an air space formed by a vane, a groove, and a side board and by controlling the oil supply to the vane by means of the pressure in the vicinity of a discharge port.

CONSTITUTION: When the pressure in front of a discharge valve 15 is high, a valve body 21 is pressed down and oil passages 19 and 20 are connected to each other so that lubricating oil is sent to the bottom 13. When the pressure is low, inversely, the valve body 21 is pressed up and the oil passages 19 and 20 are closed. Thus the lubricating oil cannot be supplied in, creating noise. However, because of a throttle passage 18 provided between passages 16 and 17, 4-cycle pulsation for one revolution is damped, and the pressure in front of a discharge valve 15 becomes equal to or higher than that at the rear of the discharge valve 15 so that the valve body 21 is stabilized during operation. Accordingly, upon stoppage of the compressor, intrusion of the lubricating oil into a cylinder 1 as well as reverse turning of rotor 6 can be prevented in a very short time.