To provide a technique for improving the convenience of a user while protecting the copyright of contents.

A device receives contents usage information from a storage device, decrypts encrypted contents data using a contents key contained in the contents usage information thus received, stores status information which indicates the use state of the contents usage information, measures elapsed time for decryption of the encrypted contents data using the contents key, or elapsed time for reproduction of the contents data decrypted using the contents key, determines whether or not the contents usage information is used, based upon the elapsed time thus measured and reflects determination of consumption of the contents usage information on the state information to be recorded in a log storage part.