Compressor bodies, an accelerator and a main motor are disposed on a base, while an intercooler, an aftercooler, an oil cooler and a coolant cooler are disposed perpendicular to the axial direction of the motor so that the directions, in which the tube nests of the gas coolers are drawn out, are made to be the same. A control panel having a maintenance display is mounted on a front panel composed of panel portions which are mounted pivotally around respective remote or opposite side ends. Portions to be inspected daily are disposed near the front panel and one side panel adjacent thereto. The compressor bodies including rotors that have been coated with a melted and solidified substantially homogeneous and continuous layer of a tetrafluoroethylene-perfluoroalkylvinylether copolymer that is substantially devoid of pinholes.