The invention relates to a piston pump, in particular a high-pressure fuel pump, comprising a housing (1), a piston and a drive shaft (2) having a cam section (3) on which the piston is at least indirectly supported via a guide roller (5) that is rotatably mounted in a roller plunger (4), wherein laterally on either of the two sides of the cam section (3) a rim (6) is provided that protrudes in the radial direction beyond the cam section (3), wherein the rim (6) tapers on one front face directed towards the guide roller (5) to an outer circumference of the rim (6), wherein the rim (6) is in particular conical, so that an angular opening results, wherein the cam roller comprises a convex curvature directed towards the rim (6), preferably with a radius (r). Alternatively, also the rim can have a convex curvature and the roller can taper conically.