A vane of a first cylinder is compressed and urged by a spring member. A vane of a second cylinder is compressed and urged corresponding to a differential pressure between an intra-casing pressure guided into a vane chamber and a suction pressure or discharge pressure guided to the cylinder chamber. A pressure shift mechanism which guides the suction pressure or discharge pressure has a branch pipe having a one end connected to a high pressure side of the refrigeration cycle, an other end connected to a suction pipe, and a first on-off valve in a midway portion, and a second on-off valve or a check valve which is provided in the suction pipe on a side upstream of a connection portion of the branch pipe and on a side downstream of an oil returning opening in an accumulator.