1. An object identification apparatus which identifies a class of a plurality of registered classes to which an object in an input image belongs, comprising: a storage unit configured to store a plurality of registered images used in identification of the object in the input image; a holding unit configured to hold designation data to designate partial areas used in identification; an identification unit configured to extract feature amounts of the partial areas designated by the designation data from the input image and each of the plurality of registered images, and to identify a class to which the object in the input image belongs based on the extracted feature amounts; a registration unit configured to register a new image in said storage unit; a determination unit configured to determine based on the plurality of registered images stored in said storage unit whether or not to update processing to be performed by said identification unit, if the new image has been registered by said registration unit; and an update unit configured to update, when said determination unit determines that the processing is to be updated, the designation data held by said holding unit based on the registered images stored in said storage unit, wherein said identification unit comprises: a standard identifier in which parameters are set by learning using a plurality of supervisory images; adaptive identifiers for respective classes, in each of which parameters are set using registered images registered in said storage unit; a calculation unit configured to calculate a first identification ratio using only the standard identifier and a second identification ratio using both of the standard identifier and an adaptive identifier; a parameter update determination unit configured to determine whether or not to update the parameters, based on a magnitude relationship between the first identification ratio and the second identification ratio; and a parameter update unit configured to update, when said parameter update determination unit determines that parameters are to be updated, the parameters based on registered images registered in said storage unit.