PURPOSE: To facilitate the operation of a special vehicle by providing a proceeding turn setter for setting the proceeding direction and turning direction of the special vehicle, integrally with a driving operator's seat, and controlling a left or right hydraulic pump device according to the output of the proceeding turn setter.

CONSTITUTION: In the case of operating a rubber crawler carrier 100A forward, a handle 1a is operated forward. This operation signal is inputted along with a forward position signal to a control part 3 from a seat position detecting part 2 so as to output control currents ILL, IR1 proportional to the operating quantity of the handle 1a. Hydraulic pump devices 105A, 109A are thereby driven to rotate a lateral pair of hydraulic motors 106, 110 in the forward direction. In the case of a seat being in a reverse position, the reversal signals of a proceeding direction signal and a turning direction signal are outputted from the control part 3 in association with the input of a rear position signal from the seat position detecting part 2. Operation can thereby be performed with normal feelings in a normal position.