To reduce a piping space of hydraulic piping from control valves to right and left hydraulic motors though control signals are transmitted to the right and left hydraulic motors by the hydraulic piping from the control valves in a tractor having the right and left hydraulic motors for driving a traveling device.

This structure is so constituted that hydraulic piping 17, 23 for transmitting control signals from control valves 15, 16 for controlling right and left hydraulic motors 11, 11 are provided, a branching part 18 is provided on the hydraulic piping 17, 23, and the control signals are transmitted to the right and left hydraulic motors 11, 11 by the hydraulic piping branched from the branching part 18. When the hydraulic pipings are piped from the branching part 18 to the right and left hydraulic motors 11, 11, a piping space from the control valves 15, 16 to hydraulic motors 11, 11 can be reduced.