Maintenance Method for Scroll Fluid Machine, and Scroll Fluid Machine

A maintenance method for replacing a main body unit on a scroll fluid machine including the main body unit that has a fixed scroll, an orbiting scroll for forming working chambers between itself and the fixed scroll, a support supporting the orbiting scroll for orbiting motion thereon, and a main body casing connected to the fixed scroll and accommodating the orbiting scroll and the support therein, and a motor unit that is connected to the main body unit to allow the orbiting scroll to undergo orbiting motion via a crankshaft, wherein the motor unit has a flange having a protruding portion that extends toward the main body unit and has an outer circumferential side first fitting surface and an outer circumferential side second fitting surface at positions different from each other in a circumferential direction or a radial direction,

• the main body casing of the main body unit before the replacement has an inner circumferential side third fitting surface fitted on only the first fitting surface, and the main body casing of the main body unit after the replacement has an inner circumferential side fourth fitting surface fitted on only the second fitting surface.