1. An image processing apparatus comprising: a first calculation unit constructed to calculate a feature amount of a query image serving as a query; a second calculation unit constructed to calculate a first similarity between a feature amount of each image stored in a storage device and the feature amount calculated by said first calculation unit, thereby obtaining a plurality of candidate images similar to the query image based on the calculated first similarity; a selection unit constructed to select a device as a reference target when an image search process is instructed; and a display order determination unit constructed to determine a display order of the plurality of candidate images obtained by said second calculation unit according to second similarities between each of the plurality of candidate images and images processed in the past by the device selected as the reference target, the second similarities being calculated on the basis of a log of the device selected as the reference target, the log containing data of at least one process performed on image data in the past by the device selected as the reference target, wherein the second similarities are different from the first similarity.