There is provided an ink jet printing apparatus that suppresses density unevenness caused by a difference in print time resulting from printing based on a bidirectional multi-pass printing system. With a relatively small print medium width, the time difference unevenness does not occur even in 2 pass printing. Accordingly, the 2 pass printing is selected. With a relatively large print medium width, selection of the 2 pass printing may make the density unevenness significant. Accordingly, the density unevenness is suppressed by selecting 8 pass printing. That is, in the 8 pass printing, the same area is scanned eight times, which is four times as frequent as the twice in the 2 pass printing. This reduces the size of each area having different densities, while increasing a cycle frequency at which a high and low densities are alternately repeated. As a result, the time difference unevenness is not perceived easily.