A controller (20) estimates an internal cylinder pressure of an engine (1) on the basis of the operating conditions of the engine (1), torque variation in the engine (1) is calculated on the basis of the estimated internal cylinder pressure, and an opposite phase torque of the torque variation in the engine (1) is calculated as a torque correction amount. The controller (20) then calculates a torque command value for a motor generator (2) by adding the torque correction amount to a basic torque value for driving the motor generator (2) to rotate, and performs torque control such that the torque of the motor generator (2) equals the torque command value.