An AC-coupled interface circuit on a semiconductor integrated circuit apparatus performing a bidirectional data transfer via a differential transmission line includes a differential driver, a differential receiver and a potential setting section. The differential driver includes a pair of output terminals connected to a pair of signal lines. The differential receiver includes a pair of input terminals connected to the pair of signal lines. In a data transmission operation, the differential driver converts transmit data to a differential signal to output the differential signal. In a data reception operation, the differential receiver receives a differential signal transferred to the pair of signal lines and converts the differential signal to receive data. The potential setting section sets a potential of the pair of signal lines to a predetermined stable potential before the differential signal is transferred to the pair of signal lines.