A fluid machinery including: an expander that generates power by expansion of refrigerant; and a piston pump that pumps the refrigerant, and capable of reducing a decrease in lubrication performance of a mechanical sliding section in a crank chamber of the piston pump. A fluid machinery 29A includes an expander unit (scroll expander) 60A that generates power by expansion of refrigerant, and a pump unit (piston pump) 50A that pumps the refrigerant. A rotating shaft 28 of the fluid machinery 29A functions as an output shaft of the expander unit 60A and a drive shaft of the pump unit 50A. The rotating shaft 28 has a crank section 28a housed in the crank chamber 72A. A refrigerant outlet chamber 78A, through which the expanded refrigerant is discharged from the expander unit 60A, communicates with the crank chamber 72A via a bearing 71b, a housing space of a driven crank mechanism 80, and an anti-rotation member 77.