In a direct current electric motor, segment pieces of a commutator are generally planar and are arranged one after another in a circumferential direction about a rotational axis of the commutator. A slidably engaging surface of each segment piece, which is slidably engageable with a plurality of brushes of the motor, extends in a plane that is generally perpendicular to the rotational axis, and each segment piece includes a radially inner engaging portion at a radially inner end part of the segment piece. Each conductive line extends along a corresponding straight line and electrically interconnects between the radially inner engaging portions of corresponding two of the plurality of segment pieces to implement the same electric potential in the corresponding two of the plurality of segment pieces.