To permit the protection of copyright of content and admit the reproduction of the content within a range of personal use by a method alleviating a load on a user.

If content data are to be transmitted to an external data use device, attribute information which is a reduced value obtained by multiplying a remaining validity period by a prescribed positive multiplier smaller than one as an expiration date from the current time is transmitted together with the content data. If content data and attribute information transmitted from an external data use device are received and attribute information including identical attribute identification information is present in own recording means, attribute information including a longer expiration date is overwritten on attribute information including a shorter expiration date.