For a serial inkjet printing apparatus that performs printing by employing ink having different properties, the occurrence of smear is prevented without decreasing the printing speed more than necessary. A high duty area, i.e., a unit area for which a large amount of ink is applied, is detected in a preceding printing medium. Then, while taking into account the scanning direction (ink application order) in which the detected high duty area has been printed, the period until the following printing medium is permitted to contact the high duty area is determined. Then, during printing of the following printing medium, the printing operation is delayed, so that, within the determined period of time, the following printing medium does not contact the high duty area of the preceding printing medium.