An object of the invention is to provide a compressor that includes a corrosion-resistant film formed on the surface of a casing having a complicated shape. A compressor pumps gas in a compression chamber formed by a casing, the casing is made of cast iron, and a layer made of a mixture of iron nitride and a compound of iron, nitrogen, and carbon and an oxide layer made of triiron tetraoxide are formed on the surface of the casing. Accordingly, since the corrosion resistance of the casing, which includes a film formed by a gas soft-nitriding treatment and an oxidation treatment, is improved, the generation of rust is suppressed. Therefore, it is possible to provide a compressor in which galling or sticking caused by rust occurs less.