An ink jet printing apparatus is provided which is capable of producing an image with a good balance between image quality and printing speed, without unduly shortening a longevity of a print head, even when an odd-numbered-pass bidirectional printing is performed. To this end, during a bidirectional multi-pass printing with a relatively small number of passes, a stepping mask is used to eliminate image problems caused by a difference in print permitted ratio between forward scan and backward scan. During a bidirectional multi-pass printing with a relatively large number of passes, a flat mask is used to give priority to suppressing density unevenness resulting from nozzle characteristic variations. As a result, the printing apparatus as a whole can produce an image with a good balance between image quality and printing speed, without unduly shortening a longevity of the print head.