Patent ID: 7931348

Claim:
An ink jet printing apparatus that uses a print head on which a plurality of ejection ports are arranged to cause the print head to scan a printing medium while ejecting ink to the printing medium during the scan of the print head, to perform printing, said apparatus comprising: a pattern printing unit for performing printing of respective predetermined patterns by an upstream side ejection port and a downstream side ejection port, which are different in positions in a conveying direction of the printing medium, among the plurality of ejection ports; a detecting unit for detecting densities of the respective predetermined patterns of the upstream side ejection port and the downstream side ejection port, which are printed by said pattern printing unit, and detecting a difference between a distance between the upstream side ejection port and the printing medium and a distance between the downstream side ejection port and the printing medium, based on the detected respective densities; and an adjusting unit for performing an operation for changing the distances between the respective upstream and downstream side ejection ports and the printing medium, based on the difference of the distances detected by said detecting unit.