A vane type rotary compressor has a housing and end plates secured thereto to cooperate therewith to define a cylindrical bore in which a rotor is eccentrically mounted for rotation with vanes slidably mounted in vane grooves formed in the outer periphery of the rotor. A lubricant groove is formed in the inner surface of one end plate and so disposed as to be brought into communication with the inner end portions of the vane grooves pertaining to vanes defining working chambers when in their intake phases. The lubricant groove is connected by a passage with a discharge chamber of the compressor so that fluid pressure is fed into the inner end portions of the vane grooves to urge the vanes into sealing engagement with the inner peripheral surface of the cylindrical bore. A valve is provided to disconnect the discharge chamber from the lubricant groove during normal compression operation of the compressor.