To compact a variable capacity type piston pump, constituting a power source for a construction machine of a shovel, etc., and also improve efficiency, and prevent the pollution of a pressurized oil and so on.

A variable capacity type piston pump is equipped with a cylinder block 2, for rotating integrally with a pump spindle 1; cylinder arrays 4a and 4b, formed in a cylinder block, and for housing reciprocatingly and slidably pistons 41 and 42; and a swash plate 50 for adjusting strokes of the reciprocating movement of the pistons. A group of ports 21, 22, and 23, communicated with cylinder chambers 24a, 24b, and 25 are formed on three or more concentric circumferential positions, having different diameters with each other, on the port side end surface 2a of the cylinder block. A suction side penetration hole, for communicating concurrently with about a half number of the port group, is formed in the suction side range of a valve plate 3 joined to the port side end surface; while, three or more delivery side penetration holes 32, 33, and 34, for communicating concurrently with the about half number of the port group formed on the concentric circumferential position, are formed on a delivery side. Then, a pressurized oil is independently discharged respectively, from the respective delivery side penetration holes, by the reciprocating movement of the pistons following the rotation of the cylinder block.