To provide a sub-image search apparatus and a sub-image search program that can quickly and accurately search even sub-images in images.

Image data to be accumulated are divided into a plurality of areas and assigned area number data, and feature quantity data of each area are extracted. As for search object image data, similarly, area number data are assigned and search feature quantity data are extracted. Similarity between the feature quantity data is first determined to search to narrow down similar image data. The area number data assigned to pixels of each area are next used for narrowing down to search of area shapes. A comparison of a rectangular area circumscribing each area or a comparison of the actual shape of each area is made in terms of overlap area.