An image processing apparatus according to an aspect of the present disclosure includes an optical character recognition (OCR) unit configured to sequentially execute processing related to OCR on image data on a plurality of documents, a generation unit configured to select one of the plurality of documents subjected to the processing related to OCR, and to generate a recommendation content about an index to be assigned to the one selected document based on an index extraction rule, and a confirmation unit configured to present the generated recommendation content to a user and to assign an index to the one document based on an instruction from the user. The processing to be executed by the OCR unit and processing to be executed by the confirmation unit are executed in parallel.