To provide a method of determining the reference position of grooved rolling rolls, capable of easily determining the reference position for adjusting the pressing position of the groove rolling rolls arranged in a rolling stand, and capable of easily calibrating the pressing position.

In the rolling stand 200, there are arranged the two grooved rolling rolls R11, R12 which are adjustable in position in a direction X perpendicular to the pressing direction Y. The method of determining the reference position of the grooved rolling rolls includes moving the grooved rolling roll R11 provided with a third straight part L3 or the grooved rolling roll R12 provided with a fourth straight part L4 in the direction Y perpendicular to the pressing direction X until the third straight part L3 of the grooved rolling roll R11, which is provided with the third straight part L3, contacts with the fourth straight part L4 of the grooved rolling roll R12, which is provided with the fourth straight part L4, under a constant load.