Provided is a compound motor (14) comprising: a magnet rotor (19) rotatably supported by a plurality of bearings (B3, B4); a wound rotor (20) comprising a rotor coil (20b) and supported by a plurality of bearings (B5, B6) on the inner side of the magnet rotor (19) so as to be rotatable relative to the magnet rotor (19); and a plurality of slip ring mechanisms (25). A space is formed on the inner periphery of the wound rotor (20), at least some of the plurality of slip ring mechanisms (25) are disposed in the space on the inner periphery of the wound rotor (20), the bearings (B3-B6) include bearings (B3, B6) with inner diameters larger than the radial direction size of the slip ring mechanisms (25), and the bearings (B3, B6) are disposed on the radial outer side of the slip ring mechanisms (25).