A rotor of an electric motor includes a plurality of magnets arranged in a circumferential direction. The rotor includes a holding member mounted concentrically with the rotor and on a radially outside of the magnets so as to hold the magnets. The holding member includes a plurality of tubular members having different diameters and being arranged concentrically with one another. The respective tubular members have expanded diameters, and therefore, compressive holding force acts on the magnets from the holding member, as a result of elastic restorative force. The tubular members include tubular members having different mechanical properties.