ROTATING ELECTRICAL MACHINE

An electric motor includes a housing, a rotary shaft supported rotatably by the housing, a rotor fixed to the rotary shaft, and a stator fixed to the housing and provided opposite the rotor on a radial direction outer side of the rotor, wherein the stator includes a stator core formed by laminating a plurality of steel plates, the stator core is fixed to a stator attachment surface provided on an inner peripheral surface of the housing, and an inner diameter expansion region is provided adjacent to the stator attachment surface on the inner peripheral surface of the housing in a position corresponding to an end part of the stator core, the inner diameter expansion region having a larger diameter than the stator attachment surface so as not to contact the stator core. As a result, deformation of the laminated steel plates forming the stator core can be prevented by means of a simple structure.