1. An image processing apparatus comprising: a memory for storing a program; a processor which executes the program stored in the memory to: input an object area of an image for learning; and learn information concerning a feature quantity of the object area using the feature quantity extracted from the input object area of the image for learning, wherein the learning learns the image feature of the object area as a combination of the image features for each partial area obtained by dividing a circumscribed rectangle of the object area into a predetermined number of partial areas, and generates the image feature of each partial area by using information of pixels included in the object area in the partial area; acquire an image including an object; divide the acquired image into a plurality of superpixels based on similarity of pixel values of adjacent pixels; generate a plurality of candidate areas for an area of the object by combining respective combinations of two or more superpixels in the plurality of superpixels, wherein the candidate areas correspond to different combinations of the superpixels; extract a feature quantity from each of the plurality of candidate areas; check the feature quantity extracted from each candidate area, against registered information concerning the feature quantity of the object area; and output the area of the object in the acquired image, based on a checked result for each candidate area by the checking.