<p>In a configuration in which a first shaft portion configured to drive a pump mechanism and a second shaft portion configured to drive an expansion mechanism are coupled to each other, a Rankine cycle system which is capable of continuing the circulation of working fluid by an expansion machine even when the pump mechanism is locked is provided. This Rankine cycle system of the invention employs a pump 1 and an expansion machine 5 coupled in a tandem manner. A first shaft 30 of the pump 1 and a second shaft 32 of the expansion machine 5 are concentric and the first shaft 30 is capable of transmitting power to the second shaft 32. A pump torque limiter 43 is provided between the first shaft 30 and a main gear 41. A one-way clutch 65 is provided between a sensing shaft 61 and the second shaft 32.</p>
