A rotor comprising: a circular rotor core; a plurality of plate-like magnets; and a pair of ring-shaped auxiliary magnets disposed, in both end faces of the rotor core in a direction of a rotating shaft thereof, respectively, in such a manner as to face the rotor core, wherein the rotor core has a plurality of magnet holding sections formed radially with the rotating shaft as a center, wherein the plate-like magnets are held in the magnet holding section such that the same magnetic poles of adjacent magnets face each other in a circumferential direction of the rotor core, wherein the rotor core is such that an N-pole and an S-pole are alternately formed in a circumferential direction of an outer circumferential surface of the rotor core, wherein the auxiliary magnets are such that an N-pole and an S-pole are alternately formed circularly on an opposed face of the auxiliary magnet facing an end face of the rotor core in the direction of the rotating shaft thereof, characterized in that the auxiliary magnets are provided such that, in a phase in a rotational direction of the rotor core, the phase of the N-pole of the opposed face is shifted relative to the phase of the N-pole in the outer circumferential surface of the rotor core, wherein, when the phase of the N-pole of the opposed face of the auxiliary magnet is shifted relative to the phase of the N-pole in the outer circumferential surface of the rotor core, a shift length X [mm], relative to a position of the N-pole in the outer circumferential surface of the rotor core, at a position shifted in the rotational direction of the rotor core in an outer circumferential part corresponding to the phase of the N-pole of the opposed face of the auxiliary magnet, is so set as to satisfy 0.2 ≤ X / Lm ≤ 2.0, where Lm [mm] is the thickness of the plate-like magnet in the circumferential direction of the rotor core, and wherein the number Q of magnetic poles of the auxiliary magnets is identical to the number P of magnetic poles of the rotor. a circular rotor core; a plurality of plate-like magnets; and a pair of ring-shaped auxiliary magnets disposed, in both end faces of the rotor core in a direction of a rotating shaft thereof, respectively, in such a manner as to face the rotor core, wherein the rotor core has a plurality of magnet holding sections formed radially with the rotating shaft as a center, wherein the plate-like magnets are held in the magnet holding section such that the same magnetic poles of adjacent magnets face each other in a circumferential direction of the rotor core, wherein the rotor core is such that an N-pole and an S-pole are alternately formed in a circumferential direction of an outer circumferential surface of the rotor core, wherein the auxiliary magnets are such that an N-pole and an S-pole are alternately formed circularly on an opposed face of the auxiliary magnet facing an end face of the rotor core in the direction of the rotating shaft thereof, the auxiliary magnets are provided such that, in a phase in a rotational direction of the rotor core, the phase of the N-pole of the opposed face is shifted relative to the phase of the N-pole in the outer circumferential surface of the rotor core, wherein, when the phase of the N-pole of the opposed face of the auxiliary magnet is shifted relative to the phase of the N-pole in the outer circumferential surface of the rotor core, a shift length X [mm], relative to a position of the N-pole in the outer circumferential surface of the rotor core, at a position shifted in the rotational direction of the rotor core in an outer circumferential part corresponding to the phase of the N-pole of the opposed face of the auxiliary magnet, is so set as to satisfy 0.2 ≤ X / Lm ≤ 2.0, where Lm [mm] is the thickness of the plate-like magnet in the circumferential direction of the rotor core, and wherein the number Q of magnetic poles of the auxiliary magnets is identical to the number P of magnetic poles of the rotor.