1. An apparatus comprising: an acquisition unit configured to acquire one or a plurality of candidates for a size of a printing medium, wherein the one or the plurality of candidates are based on a detection result by a sensor for detecting the size of the printing medium; and a printing control unit configured to cause a printing unit to print on the printing medium an image, wherein if the plurality of candidates acquired by the acquisition are narrowed down to one candidate corresponding to a combination of a plurality of conditions, the printing control unit causes the printing unit to print an image having a size corresponding to the one candidate, and wherein if the plurality of candidates cannot be narrowed down to one candidate by the plurality of conditions, the printing control unit causes the printing unit to print an image having a size corresponding to a candidate specified according to a predetermined priority order for a size of a printing medium.