1. An image detection apparatus for detecting a target in an input image, comprising: a database storing at least one target data unit, each of the at least one target data unit including information specifying the target to be detected, used color data representing a plurality of used colors which are used in the target, representative color data representing a representative color selected from the plurality of used colors, and a cluster image representing a positional arrangement of a plurality of areas respectively having the plurality of used colors; a representative color area extraction section for receiving the input image and information specifying the target to be detected in the input image, specifying a target data unit, from among at least one target data unit stored in the database, which corresponds to the information specifying the target to be detected in the input image, and extracting from the input image, as a representative color area, at least one area having substantially the same color as the representative color represented by the representative color data included in the specified target data unit; a candidate area extraction section for obtaining at least one candidate area possibly including the target from among the at least one representative color area extracted by the representative color area extraction section, using relative positions of an area having the representative color in the cluster image included in the specified target data unit and a frame of the cluster image; and a comparison section for comparing the cluster image included in the specified target data unit and each of the at least one candidate area obtained by the candidate area extraction section, and detecting one of the at least one candidate area obtained by the candidate area extraction section based on the comparison result as an area including the target.