The present invention provides a dynamoelectric machine that suppresses the occurrence of insulation failure that accompanies oxidation of a stator core without lowering output, and that also suppresses stator temperature increases by transferring heat that is generated in a stator coil efficiently to a frame. A stator core is configured by laminating and integrating thin magnetic plates, and has an outer circumferential surface that has a cylindrical surface, and receiving grooves are formed on inner circumferences of openings of frames. The receiving grooves are constituted by: an annular axial surface that is constituted by a flat surface that is perpendicular to a central axis of the stator core; and a radial surface that is constituted by a cylindrical surface that is centered around the central axis. Metal surfaces of the thin magnetic plates at two axial ends of the stator core are held between each of the axial surfaces of the pair of frames in a state of close contact around an entire circumference.