To prevent illegal duplication actions regarding a content distribution device.

This content distribution device 1 is provided with an authentication processing part for performing an authentication processing by using individual number information inputted for purchase and used for the account settlement for the purchase of contents 151 and a cipher processing part 12 for ciphering the contents by using the individual number information and distributing them. This content perusal device 2 is provided with a browser 161 for perusing the contents 152 (151) which are the contents ciphered by using the individual number information and including the individual number information. The browser 161 displays the individual number information and then displays the contents 151 on the basis of the ciphered contents 152.