An object is to reduce operation load on a user when correcting the positional shift of tab document data with respect to a tab sheet. This invention provides a document processing method of a document processing apparatus, which includes acquiring tab sheet information to be used for printing, determining, based on the acquired tab sheet information and document data containing tab print data to be printed on the tab portion of a tab sheet, whether the tab print data is allocated on the tab portion of the tab sheet, and if it is determined that the tab print data is not allocated on the tab portion of the tab sheet, shifting the tab print data, based on the acquired tab sheet information and the document data containing the tab print data, so as to be allocated on the tab portion of the tab sheet.