Abstract: To abolish the O-ring for sealing the space on the rotor shaft rear end surface side. There are provided at the ends of a tubular cylinder a front side block and a rear side block, and a rotor rotatable by a rotor shaft is arranged in a cylinder, there being formed in the rotor vane grooves in which vanes are accommodated so as to be capable of advancing and retreating and vane back pressure chambers, there being further provided a high pressure chamber and an oil sump portion, a lubricant oil space being provided in the rear side block and on the rear end surface side of the rotor shaft, there being provided an oil supply passage for supplying oil to the lubricant oil space from the oil sump portion, there being provided in the rear side block or in the rotor shaft a vane back pressure chamber oil passage 40 whose one end communicates with the oil accommodating space and whose other end communicates with the vane back chambers.