An object discriminating apparatus is provided with an obtaining unit configured to obtain an input image including an object; an extracting unit configured to extract a feature from the input image; a calculating unit configured to calculate, by collating the feature extracted from the input image and a feature of a previously registered registration image with each other, similarity between the object included in the input image and an object included in the registration image; a deriving unit configured to derive a difference between a variation in the input image and a variation in an output image; a converting unit configured to convert the calculated similarity on the basis of the derived difference between the variations; and a deciding unit configured to decide, on the basis of the converted similarity, whether or not the object included in the input image is identical with the object included in the registration image.