1. An image processing apparatus that retrieves a specific image including a specific object area from a plurality of images, comprising: a storage unit configured to store management information of each of the images; a determination unit configured to determine whether or not object search information exists in the management information; a first processing unit configured to, in a case where said determination unit determines that the object search information does not exist, refer to an object dictionary in which feature items of objects are registered, and compare a feature item of an object detected from an image and the feature items of the object dictionary to thereby retrieve candidate images as candidates of the specific image; and a second processing unit configured to, in a case where said determination unit determines that the object search information exists, retrieve the candidate images based on the object search information.