In a vehicle equipped with both an engine and a motor as the driving power source, in the event of incompletion of learning a control demand for regulation of an idling rotation speed of the engine, intermittent operation prohibition control of the invention permits intermittent operation of the engine under the setting of a gearshift lever to a parking position. The intermittent operation prohibition control of the invention prohibits the intermittent operation of the engine, on the other hand, under the setting of the gearshift lever to a drive position. This arrangement avoids the continuous operation of the engine against the driver's expectation, while prohibiting the intermittent operation of the engine to ensure the opportunity of learning the control demand for regulation of the idling rotation speed of the engine.