A hydraulic rotary machine of a variable displacement type, the hydraulic rotary machine comprising: a housing; a rotor shaft rotatably supported by the housing; a cylinder block that includes a plurality of cylinders intermittently disposed around the rotor shaft and revolves together with the rotor shaft about a central axis of the rotor shaft; a plurality of pistons that are each housed in each of the plurality of cylinders in the cylinder block and reciprocates in an axial direction in the cylinder along with rotation of the cylinder block; a retainer bush that includes a bush outer circumferential surface and is supported on the rotor shaft to rotate about the central axis along with rotation of the rotor shaft, the bush outer circumferential surface having a spherical shape that swells outward in a radial direction of the rotor shaft and has a first curvature; a retainer that has a retainer inner circumferential surface and is supported on the retainer bush to rock about an axis perpendicular to the rotor shaft, the retainer inner circumferential surface having a concave spherical shape that has the first curvature and is slidably fit on the bush outer circumferential surface; a plurality of piston rods that are disposed to extend in the axial direction and connect the plurality of pistons and the retainer, the plurality of piston rods rotating the retainer about the central axis along with the plurality of pistons revolving about the central axis; a swash plate that is disposed in a side opposite the cylinder block in the axial direction to oppose the retainer and supported by the housing to rock about the axis; a thrust bearing that is interposed between the swash plate and the retainer in the axial direction and supports the retainer to allow the retainer to rotate about the central axis relative to the swash plate; and a tilt regulation mechanism that regulates a moving distance in the axial direction of the reciprocating piston by rocking the swash plate about the axis and rocking the retainer about the axis via the thrust bearing with the retainer inner circumferential surface sliding against the bush outer circumferential surface, characterized in that the hydraulic rotary machine further comprises: a block supporting portion that is a ring-shaped member in contact with the bush outer circumferential surface of the retainer bush, the portion of the block supporting portion that is in contact with the bush outer circumferential surface having a spherical shape having the same curvature as the retainer inner circumferential surface of the retainer; and a block urging spring that is a spring member interposed between the block supporting portion and the cylinder block and urges the cylinder block. a housing; a rotor shaft rotatably supported by the housing; a cylinder block that includes a plurality of cylinders intermittently disposed around the rotor shaft and revolves together with the rotor shaft about a central axis of the rotor shaft; a plurality of pistons that are each housed in each of the plurality of cylinders in the cylinder block and reciprocates in an axial direction in the cylinder along with rotation of the cylinder block; a retainer bush that includes a bush outer circumferential surface and is supported on the rotor shaft to rotate about the central axis along with rotation of the rotor shaft, the bush outer circumferential surface having a spherical shape that swells outward in a radial direction of the rotor shaft and has a first curvature; a retainer that has a retainer inner circumferential surface and is supported on the retainer bush to rock about an axis perpendicular to the rotor shaft, the retainer inner circumferential surface having a concave spherical shape that has the first curvature and is slidably fit on the bush outer circumferential surface; a plurality of piston rods that are disposed to extend in the axial direction and connect the plurality of pistons and the retainer, the plurality of piston rods rotating the retainer about the central axis along with the plurality of pistons revolving about the central axis; a swash plate that is disposed in a side opposite the cylinder block in the axial direction to oppose the retainer and supported by the housing to rock about the axis; a thrust bearing that is interposed between the swash plate and the retainer in the axial direction and supports the retainer to allow the retainer to rotate about the central axis relative to the swash plate; and a tilt regulation mechanism that regulates a moving distance in the axial direction of the reciprocating piston by rocking the swash plate about the axis and rocking the retainer about the axis via the thrust bearing with the retainer inner circumferential surface sliding against the bush outer circumferential surface, a block supporting portion that is a ring-shaped member in contact with the bush outer circumferential surface of the retainer bush, the portion of the block supporting portion that is in contact with the bush outer circumferential surface having a spherical shape having the same curvature as the retainer inner circumferential surface of the retainer; and a block urging spring that is a spring member interposed between the block supporting portion and the cylinder block and urges the cylinder block.