A piston pump includes a piston assembly which has at least one transverse bore which corresponds to a longitudinal bore. The piston pump further includes a cylinder in which the piston assembly is guided in a longitudinally movable manner, and an inlet valve which includes a cage element, in which an inlet valve spring and sealing element are arranged, and a corresponding inlet valve seat which is arranged on the piston assembly. The inlet valve sealing element can be pressed sealingly into the corresponding inlet valve seat by means of a restoring spring in order to close off the longitudinal bore. The restoring spring is designed as a simple cylindrical spiral spring which is supported axially with an upper end winding against the cage element and with a lower end winding against a cylinder base. The cage element has an elastic high-pressure sealing element which, in the direction of a cylinder wall, has a radial support region for holding and centering the upper end winding of the restoring spring. In order to guide the restoring spring, the cylinder has, at the transition between the cylinder wall and the cylinder base, a cylinder base corner radius which is adapted to the lower end winding.