To eliminate forgetfulness and delay of switch ON by avoiding complicatedness of maneuvering operation by interlocking/jointly using an ASR device and an axle-weight adjusting device.

This device has respectively slip sensors SS in both wheels of driving shafts 19, 20, and has an ASR device 1 for restraining a slip by actuating a differential brake valve 10 when detecting either one slip by the sensors SS and an axle-weight adjusting device 11 for adjusting axle-weight by adjusting air pressure of an air spring 28 by detecting the axle-weigh by an empty load detecting device 14. In this case, a jointly using control means 31 is arranged to control ON/OFF of the axle-weight adjusting device 11 and the upper limit of an axle-weight increase by being respectively connected to a controller SC of the ASR device 1 and a controller 15 of the axle-weight adjusting device 11 to automatically jointly use/actuate the axle-weight adjusting device 11 by interlocking with the ASR device 1.