To provide a fixing structure for securely fixing a stator to a housing even if shear load due to a thermal expansion difference between a stator holder for holding the stator used for a rotary electric machine and the housing occurs.

A fixing structure of a stator includes: flanges which are arranged in a stator holder, extend outward in a radial direction from one cylindrical edge, are separated in a circumferential direction and include a plurality of assembly holes; a boss which is installed in a position facing the flanges of a housing, whose inner diameter is smaller than the assembly holes, is formed with a bottom and has a plurality of fixed holes arranged in positions facing the assembly holes; and assembly pin members which are simultaneously inserted into the facing fixed holes and assembly holes, are expanded to the outside in the radial direction in the fixed holes and the assembly holes with plastic deformation and in which locking sections locked to outer peripheral edges of the assembly holes are formed on outer end faces of the flanges and which fix the flanges to the boss of the housing.