An electric motor, comprising: a housing having a tubular portion; a stator fixed to an inner periphery of the tubular portion; and a rotor arranged radially inward of the stator, and having a rotor core and a plurality of embedded magnets that are embedded in the rotor core so as to be fixed to the rotor core, the embedded magnets being arranged such that a magnetic pole with a first polarity and a magnetic pole with a second polarity are arranged alternately in a circumferential direction on an outer periphery of the rotor, wherein the rotor core is provided with a first projection that projects toward at least one axial side of the electric motor from a first magnetic pole portion of the rotor core, in which the magnetic pole with the first polarity appears in the outer periphery, and on at least one axial side of the rotor, a supplementary field magnet is arranged, which has a coil that is wound in the circumferential direction, and a yoke that serves as a magnetic path for magnetic flux produced by the coil, characterized in that second projection projects toward at least one axial side of the electric motor from a second magnetic pole portion of the rotor core, in which the magnetic pole with the second polarity appears in the outer periphery, the second projection being arranged radially inward of the first projection, and the supplementary field magnet includes an outer magnetic pole portion that faces the first projection in an axial direction, and an inner magnetic pole portion that faces the second projection in the axial direction such that a gap formed between the inner magnetic pole portion and the outer magnetic pole portion. a housing having a tubular portion; a stator fixed to an inner periphery of the tubular portion; and a rotor arranged radially inward of the stator, and having a rotor core and a plurality of embedded magnets that are embedded in the rotor core so as to be fixed to the rotor core, the embedded magnets being arranged such that a magnetic pole with a first polarity and a magnetic pole with a second polarity are arranged alternately in a circumferential direction on an outer periphery of the rotor, wherein the rotor core is provided with a first projection that projects toward at least one axial side of the electric motor from a first magnetic pole portion of the rotor core, in which the magnetic pole with the first polarity appears in the outer periphery, and on at least one axial side of the rotor, a supplementary field magnet is arranged, which has a coil that is wound in the circumferential direction, and a yoke that serves as a magnetic path for magnetic flux produced by the coil, characterized in that second projection projects toward at least one axial side of the electric motor from a second magnetic pole portion of the rotor core, in which the magnetic pole with the second polarity appears in the outer periphery, the second projection being arranged radially inward of the first projection, and the supplementary field magnet includes an outer magnetic pole portion that faces the first projection in an axial direction, and an inner magnetic pole portion that faces the second projection in the axial direction such that a gap formed between the inner magnetic pole portion and the outer magnetic pole portion.