PURPOSE: To provide a hybrid vehicle having high efficiency and high performance performance by cascading a motor generator in which a field and an armature are respectively rotatable at their output shafts between an engine and an axle driving shaft.

CONSTITUTION: The output shaft 1B of an engine 1 and an axle driving shaft 4 are respectively coupled to the field rotor shaft 3A and armature rotating shaft 3B of a motor generator 3, and a power converter 11 and a changeover switch 13 are provided between an armature coil and a battery 12. When the battery 12 is sufficiently charged, the engine 1 is stopped, the output shaft is locked by a brake 2, and the motor generator 3 is operated as a motor by the output of the battery 12. When the battery 12 is discharged, the engine 1 is started, the generator 3 is operated as a generator, and the battery 12 is thus charged.