An object identification apparatus which identifies an object included in an input image includes a unit which calculates correlation values of feature amounts in standard partial feature regions respectively extracted from the input images and processing targets, and correlation values of feature amounts in adaptive partial feature regions respectively extracted from the input image and processing targets, a unit which calculates similarities based on the calculated correlation values, and a unit which integrates the plurality of calculated similarities, and outputs them as an integrated similarity between the input image and registered image as the processing targets. According to the object identification apparatus, an identification performance between two specific categories, which are similarity to each other, is improved while maintain an overall identification performance.