To provide a high-speed wide-dynamic range differential amplifier, the amplifier comprises first and second FETs having source terminals connected to each other and a constant current source connected between the sources and ground; third and fourth bipolar transistors complementary to the first and second FETs, having base terminals connected to a first bias voltage in common and emitter terminals connected to the drains of the first and second FETs and a supply voltage via resistors, respectively; and a current mirror circuit composed of fifth and sixth FETs of the same conductive type as the first and second FETs.