Electric rotating machine suppressing narrowing of a magnetic path caused by a skin effect in a housing to increase torque, including stator core having e.g. core back and teeth; stator windings wound around the teeth; stator including stator core and stator windings; housing composed of a magnetic body accommodating the stator; rotor disposed for rotation on an inner circumferential side of the stator. An air gap is provided between an inside wall of the housing and an outer circumferential surface of core back. The core back has projections on a radial back surface of a portion where the teeth are provided. The projections are each provided to be continuous in an axial direction and have tip portions in contact with inside wall of the housing. The air gap may be defined by the inside wall of the housing, the outer circumferential surface of the core back and the projections.