Abstract: Proposed is a semiconductor device with a protection circuit that measures signal intensity and is able to prevent the occurrence of element failure due to a reflection signal or an overvoltage signal by performing adjustment of a signal path and adjustment of the signal intensity on the basis of measured signal intensity, wherein the semiconductor device includes an output signal processing terminal, an input signal processing terminal, and a wireless output-input terminal, a signal detection unit connected to the wireless output-input terminal, a first switch connected to the signal detection unit, a first resistive termination unit and a signal connection line each connected to the first switch so that the signal is able to be transferred by operation of the first switch, and a controller configured to control the first switch on the basis of the intensity of the signal.