To provide an electric-motor rotor including a cylindrical yoke, a resin magnet portion that is formed from resin magnet integrally with the outer periphery of the yoke, a position-detecting magnet that is located on one axial-end side of the resin magnet portion, a plurality of seats that are formed on the axial end surface of the yoke on the side of the position-detecting magnet, each of which includes a pair of protruding portions, and an opening formed between the protruding portions, and a seat connecting portion that is formed with the seats on its top surface, wherein a ribbed runner that supplies the resin magnet to the resin magnet portion through the opening is provided at the opening to form, along with the seat, a seat portion that places thereon the position-detecting magnet.