A dermal image information processing device including a memory; and a hardware component that reads data from the memory and is configured to: acquire dermal image information showing ridge lines in a papillary layer; detect an singular region in a pattern of the ridge lines; detect a position that is furthest away from the singular region; determine a region for collation based on the detected position; and perform collation of the pattern of the ridge lines using only feature points that are included in the region for collation.