HYDRAULIC ROTARY MACHINE

The piston pump 100 includes: a first biasing part 20 configured to bias a swash plate 8 in accordance with supplied control pressure; a second biasing part 30 configured to bias the swash plate 8 against the first biasing part 20; and a regulator 50 configured to control the control pressure guided to the first biasing part 20, wherein the regulator 50 has: a control spool 52 configured to adjust the control pressure by being moved in response to the biasing force exerted by an outer spring 51a and an inner spring 51b configured to be extended and compressed by following a tilting of the swash plate 8; an auxiliary spring 61 configured to exert the biasing force to the control spool 52 against the biasing force exerted by the outer spring 51a and the inner spring 51b; and the accommodating chamber 65 configured to accommodate the auxiliary spring 61, and the signal pressure is guided to the accommodating chamber 65, the signal pressure exerting the thrust force to the control spool 52.