Abstract: A fluid machine which can be compact and produced at reduced costs and which can increase the amount of heat added to a refrigerant circulating in a Rankine cycle and thus greatly increase the efficiency of the Rankine cycle. A fluid machine (1) comprising a pump mechanism (46) incorporated in a Rankine cycle to force a working fluid to circulate in the Rankin cycle to recover waste heat from a heat source, and an expansion mechanism (48) rotationally driven by expansion of the working fluid having been forced out by the pump mechanism (46) and then superheated, the pump mechanism and the expansion mechanism being linked by a shared drive shaft (50), wherein a pump mechanism exit section (76a) through which the refrigerant flows out of the pump mechanism (46) and an expansion mechanism exit section (76b) through which the refrigerant flows out of the expansion mechanism (48) are open outward in the same direction.