The present invention provides an ink jet printing apparatus, an ink jet printing method, a data generation apparatus, a computer program, and an ink jet printing system by which a timing for ejecting a processing liquid can be changed to improve image performance of a printed image such as abrasion resistance, to provide the printing head with a longer life, and to improve a throughput. The processing liquid is ejected to a predetermined area on a printing medium, for which a formation of an image by ink is completed, in two or more scannings among five scannings of the printing head. When an amount of ejection data for ejecting the processing liquid in the fifth scanning for ejecting only the processing liquid is equal to or lower than a predetermined amount, the fifth scanning is not carried out.