PURPOSE: To broaden a work area of a pressure switch by providing a port for pressure detection, and a change-over valve for pressure detection that communicates and cuts off the port for pressure detection and an entrance port, and by defining the change-over valve as a communicating position when the pressure of an output port is greater than a predetermined value.

CONSTITUTION: A change-over valve 11 for pressure detection that communicates and cuts off a port 10 for pressure detection and an entrance port 2, is provided on a valve main body 1. The change-over valve 11 for pressure detection forms an inflow port 16 and an outflow port 17 in a sleeve 13 inserted in a valve hole 12 of the valve 1, and the inflow port 16 is communicated with the entrance port 2, while the outflow port 17 is communicated with the port 10 for pressure detection. When a lever 6 is operated and the output pressure of an exit port 3 reaches a predetermined value, pressure is generated on the port 10 for pressure detection, whereby detection can be carried out by connecting a pressure switch. Since the work area of the pressure switch can be lengthened, a switch of low accuracy can be used.