A DVD player 11 reads disc control information recorded on a DVD medium M and causes a display 12 to display a start menu screen, thereby prompting a viewer to perform authentication (1). The viewer uses a remote controller 11a to display a first viewer authentication screen (2). Then, an acquisition code is indicated and an input of a password is requested. Here, the viewer uses a mobile telephone 13 to access the website indicated by an URL shown on the first viewer authentication screen (substantially, a server computer 2) and inputs a user ID and an acquisition code, thereby acquiring a password required for viewing the content of the DVD medium M ((3) and (4)). The viewer inputs the acquired password into the first viewer authentication screen (5). While a program recorded on the DVD medium M is executed, the DVD player 11 authenticates the password which has been input. If the password is judged to be valid, reproduction of the specified content is started.