To perform straight and turning traveling of a traveling device by faithfully following an operation by eliminating the influence of an instrumental error on performance of hydraulic equipment such as a hydraulic pump used for driving the traveling device.

This device is provided with a pair of hydraulic motors 5a and 5b for driving the traveling device 1 of a working machine due to an operation by pressure oil from the one hydraulic pump, a pair of solenoid proportional flow control valves 4a and 4b for controlling oil amount supplied to the hydraulic motors 5a and 5b, and a traveling controller (controller) 10 for making the solenoid proportional flow control valves 4a and 4b perform flow controls based on a steering set value 7a and a speed set value 8a. By preparing command signals (steering commands) e1 and e2 in a steering command circuit 11 of the traveling controller 10, delivering the signals e1 and e2 to current control devices 20 and 20, and outputting driving current corrected by instrumental error correcting devices 22 and 22 to the solenoid proportional flow control valves 4a and 4b, rotational speed of each hydraulic motors 5a and 5b is made to exactly coincide with the commands, and straight advancing and turning of the traveling device 1 are performed.