A portable terminal 20 according to the present invention is provided with an electronic book coupon storage 22, a book data receiver 24, an electronic book coupon deductor 25, and a book data decryptor 26. The electronic book coupon storage 22 stores an electronic book coupon used in acquisition of book data containing a plurality of page data units, along with a decryption key used in decryption of the plurality of page data units. The book data receiver 24 receives the book data from an electronic book providing server 30. The electronic book coupon deductor 25 deducts an electronic worth equivalent to a price according to page data requested to be readout, from the electronic book coupon. The book data decryptor 26 decrypts the page data in steps of one page data unit by use of the decryption key in conjunction with the deduction of the electronic worth.