1. An image processing apparatus, comprising: an area division unit configured to divide an image of a page to a plurality of areas; an attribute information addition unit configured to add, to the plurality of divided areas, attributes depending on the areas; a character recognition unit configured to perform a character recognition processing on a caption area and a body text area to which a caption attribute and a body text attribute are added by the attribute information addition unit, respectively; and a metadata processing unit configured to associate metadata with an object area accompanied by the caption area, wherein the metadata processing unit comprises: a first extraction unit configured to extract, from the result of the character recognition processing to the caption area, an anchor expression composed of a predetermined character string and a caption expression composed of a character string other than the anchor expression; a determination unit configured to determine whether there are a plurality of object areas accompanied by caption areas including an identical anchor expression; a second extraction unit configured to extract, from the result of the character recognition processing on the body text area, an explanatory text including the anchor expression; a first association unit configured to associate, in the case that the determination unit determines that there is one object area accompanied by a caption area including the identical anchor expression, the object area with metadata obtained from the explanatory text extracted by the second extraction unit; a similarity degree calculation unit configured to calculate, in the case that the determination unit determines that there are a plurality of object areas accompanied by caption areas including the identical anchor expression, similarity degrees between caption expressions of the respective caption areas including the anchor expression and the explanatory text including the anchor expression extracted by the second extraction unit, respectively; and a second association unit configured to determine, based on the similarity degrees calculated by the similarity degree calculation unit, such explanatory texts that are optimal for the respective plurality of object areas and to associate metadata obtained from the determined optimal explanatory texts to the respective object areas.