A waste heat recovery system includes an evaporator that evaporates a coolant in a liquid phase by using waste heat from an internal combustion engine, a turbine that rotates by receiving the coolant in a gas phase having passed through the evaporator, a condenser that condenses the coolant in the gas phase having passed through the turbine into the coolant in the liquid phase, and a pump that supplies the coolant in the liquid phase fed from the condenser to the evaporator. The waste heat recovery system further includes a coupling mechanism that constantly couples a rotating shaft of the turbine to a crankshaft of the internal combustion engine, and the crankshaft is directly coupled to a vehicle transmission.