SEMICONDUCTOR DEVICE

A semiconductor device is provided to perform operation selection of an embedded interface circuit in response to initial operation from a connected host apparatus. A first interface circuit(30) receives a clock input from a first external port and performs interface operation of a signal by using a second external port. A second interface circuit(31) does not receive a clock input from the outside, and performs interface operation of a differential signal using the second external port. A selection control circuit(32) outputs an enable signal of a first instruction signal activating interface operation of the first interface circuit by detecting the input of plural clocks supplied from the first external port when an operation voltage begins to be supplied.