To provide a device for maintaining a braking state of service brake and to prevent an equipment from being drawn by supplying specific pilot pressure to switch a service brake valve when a retractable lever is in a neutral position.

When a retractable lever 19 is in a neutral position, an electric current supplied from a battery 20 of an equipment is supplied to a working brake solenoid valve 26 through a first circuit 26a to switch a spool, and operating fluid discharged from a pump 2a driven by an engine 1 and supplied up to an inlet of valve 26 through a cut-off valve 3 acts as pilot pressure of a service brake valve 5 through the valve 26. Accordingly, the service brake spool is switched in a specific state without treading a service brake pedal by a driver, and operating fluid stored in an accumulator 4 is supplied to a service brake cylinder 7 to always operate a service brake device.