Waste heat recovery system of heat source, with rankine cycle

The system has a cooling water circuit (20) to circulate cooling water between a cooling heat exchanger and a radiator (21). Rankine cycle has a heater (210) to perform heat exchange between an operation fluid and the water to heat the fluid. Expansion device (220) expands the fluid to generate a driving power. The heater is kept parallel to the exchanger so that the water flowing through the heater bypasses the exchanger.