A false twisting apparatus comprising two endless belts crossing each other and running in opposite directions at the crossing point is disclosed, in which a yarn running through the crossing point is nipped by both the belts at the crossing point and is false-twisted by a frictional effect caused between the two belts. In this false twisting apparatus, the angle of crossing of the two endless belt is set in advance, and the apparatus may include means for detecting minute variations of this predetermined crossing angle and correcting such minute variations.