To provide a braking device to brake four wheels on a working machine for riding of four-wheel driving furnished with a differential device.

A four-wheel brake part to brake both of front wheels l with both of rear wheels 2 by transmitting braking force of at least either one of side brakes 36 in an ON working state of the left and right side brakes 36 to a main shaft 19 to transmit driving force from a transmission 16 to the side of the rear wheels 2 is constituted of an interlocking cutting work part to work to cut a differential working part 38 to carry out on-and-off operation of actuation of the differential device 21 interlocked with off-operation of a main clutch 47 of a clutch operation part 62 to operate the main clutch 47 and a connecting working part 37 to transmit braking force to the main shaft 19 by cutting work of the differential working part 38 interlocked with off- operation of the main clutch 47 of the clutch operation part 62.