There is provided an inkjet printing apparatus which performs a plurality of times of scans by a print head on a predetermined region and completes printing of the predetermined region by ejecting ink from the print head by the plurality of times of the scans, comprising generating means for performing a mask process in use of a mask to binary data of each of pixels constituting an image to be printed on the predetermined region to generate ejection data used in each of the plurality of times of the scans, wherein the mask assigns the binary data showing printing for each pixel to a plurality of times of scans among the plurality of times of the scans completing the printing to generate the ejection data for each scan of the pixel.