The differential output buffer comprises the differential output circuit, and the bias voltage generation circuit that is the replica circuit of the differential output circuit. The bias voltage generation circuit generates, by the operational amplifier, the bias voltage for controlling currents respectively flowing in the first current source of the differential output buffer and the second current source of the bias voltage generation circuit such that the voltage of the third internal node between the third internal and external resistors and the third switch of the bias voltage generation circuit becomes equal to the reference voltage equal to the voltage of the first internal node when the first switch of the differential output buffer is in an ON state or equal to the voltage of the second internal node when the second switch of the differential output buffer is in an ON state.