"According to the present embodiment, realized is the electronic content processing system that reliably restricts the use of electronic content dealt in the second-hand markets. As a result, the dealing of electronic content in the second-hand markets is suppressed, which in turn supports the redistribution of part of proceeds from sales of the electronic content to the developers. Though in the following description a game application (AP) is exemplified as the electronic content, the present embodiment is similarly applicable to various kinds of electronic content such as an office suite, images, and music content. By employing the game playing system 1000 according to the present embodiment, the use permission tag 220 together with the game disk 210 is supplied to the user, and the use permission tag 220 actively determines the use permit/rejection of electronic content. Thereby, the use of game AP stored in the game disk 210 can be restricted as appropriate according to the attribute of a reproduction device. Consider, for example, a case where used is a game package 200 distributed in the second-hand market. Then the ID of reproduction device for the game disk 210 differs from the legitimate use device ID stored in the use permission tag 220, so that the game disk can be reproduced in a mode which is predetermined for those bought and sold in the second-hand market. Also, for example, a content key may be supplied to the reproduction device 130 and the encrypted game AP may be decrypted using the content key only if the reproduction device ID matches a legitimate use device ID. Hence, use of game APs bought and sold in the second-hand market can be eliminated."