In a known fully-differential amplifier, it has been difficult to set a power voltage VDD to a low level while maintaining the signal amplitude and increase the amplitude of an output signal without increasing the power voltage VDD. The present invention provides a fully-differential amplifier including a voltage-current conversion unit, a first current-voltage conversion unit, and a second current-voltage conversion unit, where a resistance element included in the voltage-current conversion unit, a resistance element included in the first current-voltage conversion unit, and a resistance element included in the second current-voltage conversion unit are connected in parallel with one another.