1. An image search apparatus for managing image data, and searching the managed image data for desired image data, comprising: management means for managing image data and image feature amounts thereof in correspondence with each other; designation means for designating a desired one of query conditions each of which is defined by image feature amounts set with ambiguity levels; matching means for matching the image feature amounts that define the query condition designated by said designation means, with corresponding image feature amounts of image data managed by said management means; and output means for outputting image data as search results on the basis of matching results of said matching means.