1. An information processing method of identifying a class of an object by using a plurality of discriminators, said method comprising: an acquisition step of acquiring as a candidate class a class discriminated at a first stage of the discriminators; and a setting step of setting in a second stage of the discriminators, a class of the second stage of the discriminators, which is defined as an extended partial space of a partial space defined by a candidate class in a discriminating space used in discriminating the candidate class at the first stage of the discriminators, as a class to be discriminated at this second stage of the discriminators.