A catalyst is provided in an exhaust passage of an engine and an evaporating section of a heat recovery device is provided upstream of the catalyst in the exhaust passage. An ECU performs an operation for compulsorily oscillating an air-fuel ratio between a lean state and a rich state as compared to a theoretical air-fuel ratio when temperature of the catalyst reaches temperature at which the catalyst has a predetermined purification capacity after the engine is started. The ECU restricts a flow of a working fluid in the heat recovery device until the temperature of the catalyst reaches the temperature at which the catalyst has the predetermined purification capacity after the engine is started.