The present invention discovers that a rolling direction force occurs even with conventional adjustment by the kiss roll state, pinpoints that the rolling direction force does not affect the roll thrust force, and thereby enables more precise initial roll gap position adjustment of a rolling mill (rolling zero adjustment).That is, this is based on the fact that high precision rolling zero adjustment becomes possible without being affected by any thrust force acting between rolls if performing differential asymmetrical roll gap zero point adjustment of the work side and the drive side so that the difference of the rolling direction forces acting on the roll chocks of the work side and the drive side of the work roll at the work side and the drive side (in practice, within ±5% of the sum of the rolling direction forces at the work side and the drive side).