PURPOSE: To prevent accidental start of inclination of the working machine to the left or right, by releasing the means for inhibiting the inclination operation, after the actual stroke value becomes almost equal to the target value in case that the engine stops during controlling the inclination operation and is allowed to restart.

CONSTITUTION: The horizontal sensor 12 detects the inclination of the machine 1, and the hydraulic cylinder 13 is driven to control the inclination according to its extent, as the stroke value is monitored with the sensor 14. When the engine stop, while the inclination of the working machine 3 is controlled, the inclination control is not allowed to start, until the engine restarts, and the machine is allowed to run a little to recover the inclination so that the target value of stroke is coincided to the actual value or the target value is changed by turning the dial so that it is coincided with the actual value.