An electric rotary machine includes a stator, which Is fixed to a housing, composed of a stator core having a coil end protruding at an end face of the stator core, a rotor core formed by laminating core sheets, and a rotor having a pair of rotor side-plates sandwiching both end faces of the rotor core. The rotor core is rotatably supported in the housing facing an inner peripheral surface of the stator with a gap between the rotor core and the stator. Either one or both of the rotor side-plates has a concave surface in an outer surface of the side-plate that does not abut the rotor core. An axial distance from the end face of the rotor core to the concave surface increases from an inner diameter side to an outer diameter side.