A procedure for calculating a tentative engine revolution speed Netmp1 that satisfies both restriction to a driving force demand for a smooth change of a driving force acting on a drive shaft in response to a driver's release of an accelerator subsequent to the driver's accelerator actuation and a discharge limit Wout of a battery. The procedure may also calculate a smoothed engine revolution speed Netmp3 for a smooth change of a revolution speed of an engine. The procedure sets the smaller between the tentative engine revolution speed Netmp1 and the smoothed engine revolution speed Netmp3 to a target revolution speed Ne* of the engine (step S116) and controls the engine and two motors with such setting.