There is provided an ink jet printing apparatus in which unevenness that may occur at the edges of printing areas can be reduced also for various printing media including unspecified printing media. In the ink jet printing apparatus which uses a print head for ejecting ink and performs printing by scanning a predetermined area on a printing medium with the print head multiple times, the multiple times of scan including a forward scan and a backward scan, the apparatus comprising: a control unit that cases the print head to print patterns each of which is printed through multiple times of scan of the print head and has different portions in a time interval between the multiple times of scan, with different printing ratios for the multiple times of scan; and a setting unit that sets the printing ratios based on the test patterns.