A prism includes a first internal reflection interface and a second internal reflection interface. An insulating layer which covers an oxide semiconductor layer of the thin film transistor contains a boron element or an aluminum element. Thus, a user can acquire a license and key information necessary for decryption of the content, together with the content, from the information recording medium, without acquiring the license by connection to a license provider. The tester then transmits known currents though the signal paths interconnecting the tester’s IO ports.