[Objective] To improve detection performance of target tissues formed by linear structures within three dimensional images.[Constitution] The directions of principal axes of target tissues formed by linear structures or the directions of lines normal to tissues formed by planar structures within detection regions are calculated. Normalization processes are administered with respect to candidate target regions that include candidate target tissues based on the directions of the principal axes or the directions of the normal lines. Features of the normalized candidate target regions are calculated, and judgments are performed regarding whether the target tissues are included in the candidate target regions, employing the calculated features.