To store a document created on a PC and handwritten script information in association as digital data.

A dot pattern 30 for position detection, which is recognized with a digital pen 10, is printed on a rewritable sheet 20. A document D and a page section P are rewritably printed on the rewritable sheet 20 having the dot pattern thereon. Also, after a page of the document D is recognized with the digital pen 10 according to the page section P printed, a memorandum M about the document D printed is rewritably written on the rewritable sheet 20 with the digital pen 10, whereby the document D and the memorandum M are stored in association as digital data.