VEHICLE DRIVE DEVICE

When sub-field magnets 8a and 8b are not provided, the magnetic fluxes that pass through main field magnets 7a and 7b respectively and interlink with stator windings 5 and first rotor windings 6, and the magnetic fluxes that pass through the main field magnets 7a and 7b respectively and short-circuit adjacent main field magnets 7b' and 7a' are generated. The short-circuited magnetic fluxes do not contribute to torque generation, therefore a favorable inner periphery magnetic circuit is not formed, and the torque received between a second rotor 4 and a first rotor 3 becomes small. When sub-field magnets 8a and 8b are provided, on the other hand, the short-circuited magnet fluxes interlink with the first rotor windings 6 by the sub-field magnets 8a and 8b, and an inner periphery magnetic circuit is formed, whereby the motor driving torque received between the second rotor 4 and the first rotor 3 increases.