1. A document retrieving method comprising: a first acquisition step of acquiring text data based on image data of a document and acquiring text feature data based on the acquired text data; a second acquisition step of acquiring layout feature data based on the image data of the document; a storing step of storing in storage means the text feature data and the layout feature data, respectively acquired in said first and second acquisition steps, in association with the document; and a retrieving step of retrieving a document stored in the storage means using the text feature data and the layout feature data acquired by executing said first and second acquisition steps on a search document.