1. An object identification system comprising: acquiring unit that acquires a captured image of each of a plurality of objects respectively having peculiar patterns on surfaces thereof, predetermined images being formed on the surfaces; classifying unit that classifies, for each of the plurality of objects, the object into any one of a plurality of classifications according to a deviation of a position where the predetermined image is formed with respect to a reference position of the object or a pattern of noise included in the predetermined image formed on the object in the captured image acquired by the acquiring unit concerning the object; registering unit that registers, for each of the plurality of objects, identification information of the object, a pattern image indicating the pattern on the surface of the object, and a classification of the object in association with one another; classification acquiring unit that acquires candidates of classifications of a target object, which is one of the plurality of objects, on the basis of a result obtained by the classifying unit classifying the target object on the basis of a target object captured image obtained by capturing an image of the target object; pattern-image acquiring unit that acquires pattern images registered by the registering unit in association with the classifications acquired by the classification acquiring unit; and specifying unit that specifies, as identification information of the target object, identification information associated with a pattern image matching the target object captured image among the pattern images acquired by the pattern-image acquiring unit.