PURPOSE: To effectively prevent overheat of a compressor, in which an intermediate radiator is used, by preventing a heat exchange between suction gas in a suction pipe and high temperature gas in the inside of a casing in a part drawn into the casing.

CONSTITUTION: Compressed gas in a cylinder 5 is guided to an intermediate radiator 20 in the outside so as to recirculate the cooled compressed gas to the inside of a closed casing 1 through a return pipe 22. A concentrical double pipe 23, composed of an internal pipe 23a connected to a suction pipe 19 and an external pipe 23b connected to the above-mentioned return pipe 22, is formed in a connection end part in a compressor side of the suction pipe 19 to connect the above-mentioned return pipe 22 to the external pipe 23b outside the closed casing 1, and a pipe end in an internal side of the closed casing 1 of this external pipe 23b is formed as an opening end.