A plurality of patterns respectively having different area factor of dot formation area are formed by forward and reverse scanning printing of a print head, and then optical characteristics of the plurality of formed patterns are measured. A function representing the relationship between the printing position offset between the forward and reverse printings is determined from the optical characteristics. Then, respective pattern having a predetermined area factor of dot formation area is formed by means of forward and reverse scanning where the speed is differentiated according to the mode of a printing apparatus, and then the optical characteristics of this pattern is measured. By applying this measured optical characteristics to the function, an adjustment value of the dot formation position conditions between the forward and reverse scans is obtained for each mode. This makes it easy to perform printing registration in a printing apparatus in the case of printing by a forward and reverse scan of a printing head or in the case of printing by means of a plurality of printing heads. In this case, operations by a user etc. are also unnecessary and are easily performed.