In an inkjet printing apparatus, uneven density is reduced while suppressing a landing position deviation caused by a difference of head-to-medium distances in a printing medium conveying direction. Specifically, predetermined patterns for detecting a difference of the head-to-medium distances are printed. Reading of the patterns is performed and then a detection of a difference between the head-to-medium distances is performed based on the reading result. Then, adjustment of the head-to-medium distance is performed based on the difference between the head-to-medium distances detected. Specifically, the respective head-to-medium distances at the upstream side ejection port and the downstream side ejection port are made equal by changing an attitude of the print head.