Abstract: A pressure intensifier for fluids, particularly for hydraulic liquids, includes a piston/cylinder arrangement with a low pressure side provided with a low pressure connection and a high pressure side provided with a low pressure connection and a supply connection, as well as an intensifier piston constructed as a double diameter piston arranged between the low pressure side and the high pressure side. The pressure intensifier further includes a valve slide member which alternatingly connects the low pressure connection to a pressure source and a negative pressure source, wherein the control valve is connected through a control line to the piston/cylinder arrangement, so that the pressure in the control line acts on a first side of the valve slide member. The control valve is configured such that a constant force acts on a second side of the valve slide member.