1. A composite image creation assist apparatus that assists creation of a composite image using a plurality of first candidate images created by a target user, the apparatus comprising: an other user image group extraction section that extracts image groups of other users belonging to the same group as the target user based on registration information of an image service using a network; a second candidate image selection section that selects at least one second candidate image suitable for the composite image from the image groups of other users extracted by the other user image group extraction section; and a use image determination section that determines use images, which are to be used for the composite image, from the plurality of first candidate images and the second candidate image selected by the second candidate image selection section.