A rotor structure of a synchronous motor includes: a stator; and a rotatable rotor on the inner side of the stator, in which the rotor includes: a rotor core fixed to a rotary shaft; and a permanent magnet on the outer side of the rotor core, the permanent magnet on the outer side of the rotor core includes a main magnet and an auxiliary magnet, the auxiliary magnet is provided in contact with the outer side of the rotor core, and the main magnet is provided in contact with the outer side of the auxiliary magnet.