The invention relates to a switching device for a hydraulic high-pressure system, particularly for operating hydraulic screw-tightening devices, comprising: a directional seat valve (17), which is subjected to the action of high pressure in the closing direction; a control piston (22), which can be subjected to the action of low pressure and which displaces the directional seat valve in the opening direction, and, a control valve (23), which either establishes or interrupts a connection to a pressureless low-pressure return flow line.