The present invention provides a high-pressure pump having a high-pressure cylinder which has a plunger fitted in it from its top side and moving vertically. The high-pressure cylinder has at least one opening formed in its lowermost base section, so that a fluid can flow into and out of the high-pressure cylinder. A hydraulic cylinder for driving the plunger is arranged on the top side of the high-pressure cylinder. In addition, a device for preventing a fluid movement and in contact with the plunger drive shaft is arranged between the hydraulic cylinder and the high-pressure cylinder in order to prevent working fluid which flows out of the hydraulic cylinder from flowing to the surface of the plunger fitted into the high-pressure cylinder.
