To make it possible to change over the execution or the cancel of copy protection by simple constitution any time required.

A switching circuit 24 is built in a gate array part 16 on a signal pass between a scanning pass interface circuit 18 and an emulation terminal pin. A DSP 10 can access the circuit 24 through an internal bus, a logic interface circuit 26 and a logic bus, and can write required switching control information in a register stored in the circuit 24. The circuit 24 can selectively switch the circuit 18 to an enable state or a disable state by selectively switching the signal pass to an interrupted state or a conductive state in accordance with the switching control information applied from the DSP 10.