A rotating electric machine includes a field that includes a magnet unit having a plurality of magnetic poles, an armature including a multi-phase armature coil, and an electric power conversion device that is configured to perform electric power conversion and supply electric power resulting from the electric power conversion to the armature. Moreover, one of the field and the armature is configured as a rotor while the other is configured as a stator. The electric power conversion device includes at least one band-shaped busbar through which electric current flows during the electric power conversion. The at least one busbar has a cross section where a thickness in a lateral direction of the cross section at one end of the cross section in a longitudinal direction of the cross section is smaller than a thickness in the lateral direction at the other end of the cross section in the longitudinal direction.