Upon incompletion of abnormality detection of an air-fuel ratio sensor provided in an exhaust pipe of an engine during operation of the engine (steps S310 and S320), when the state of charge SOC of a battery is lower than a preset reference charge level Sref or when the accelerator opening Acc is not less than a preset reference opening Aref (steps S330 and S340), the abnormality detection is not performed (step S350). When the state of charge SOC of the battery is not lower than the preset reference charge level Sref and when the accelerator opening Acc is less than the preset reference opening Aref (steps S330 and S340), the abnormality detection is performed to identify abnormality or normality of the air-fuel ratio sensor based on an air fuel ratio AF output from the air-fuel ratio sensor (steps S360 to S420). The drive control cuts off a fuel supply to the engine, controls a motor to enable motoring of the engine, and ensures output of a torque demand to a driveshaft, while the abnormality detection is performed.