To provide a steering control device for use in a combine, that allows smoothly steering the vehicle frame to the right and left according to the amount of operation of a control lever without causing impact during switching, and that allows simplification of the constitution of the control lever.

Solenoid proportional control valves 35, 36 which are opened or closed according to detection signals of a potentiometer 31 which detects the tilt angle of a control lever are put in the hydraulic passage 32 of a hydraulic cylinder, and side clutch gears held in meshing positions are continuously operated by means of changes in current value that reacts to the detection signals of the potentiometer 31, so that the side clutch gear slides up to non- meshing positions where output shafts are held braked, via other non-meshing positions where the side clutch gears are held in neutral positions.