The present invention relates to a torsion bar for tilting the cabin of an automobile, particularly related to a torsion bar having a different number of serrations on its ends, which can improve the assembling work of the torsion and the tilting effect of the cabin. When the torsion bar is assembled to the hinge bracket and the torsion bar arm, at least one serration on the ends of the torsion bar are automatically arranged in a straight line and torque is not applied on the torsion bar.