A Rankine cycle includes an waste-heat recovery device that is configured to exchange heat between cooling water coming out from an engine and exhaust gas exhausted from the engine, a heat exchanger including an evaporator through which the cooling water coming out from the engine flows to recover waste-heat of the engine to refrigerant, and a superheater through which the cooling water coming out from the waste-heat recovery device flows to recover the waste-heat of the engine to the refrigerant, an expander that is configured to generate power using the refrigerant coming out from the heat exchanger, a condenser that is configured to condense the refrigerant coming out from the expander, and a refrigerant pump that is configured to supply the refrigerant coming out from the condenser to the heat exchanger by being driven by the expander. The cooling water coming out from the superheater is returned to the engine after being joined with the cooling water coming out from the evaporator.