A method of adjusting bidirectional registration to reduce negative effects on the image such as “banding” even if bidirectional registration includes a slight amount of displacement is provided. For that purpose, correction is applied to a first adjustment value for adjusting a bidirectional registration displacement in response to an extent of inclination of a printing head to obtain a second adjustment value. Then a bidirectional printing is performed with timing adjusted on the basis of the second adjustment value. As a result of that, even if there is a slight variation in an adjustment value of the bidirectional registration and the inclination of the printing head, the banding generated by this can be reduced as much as possible.