A current feedback-type operational amplifier comprising multiple input parts and one output part, wherein each of the multiple input parts comprises a first input terminal, a second input terminal, and an output terminal, the signals input from the first input terminal are buffer amplified and output to the second input terminal, and current is output to the output terminal in an amount corresponding to the current that flows to the second input terminal; the output terminal part comprises an input terminal and an output terminal, signals obtained by adding in terms of current the signals of all of the input parts are input to the input terminal, and the signals input to the input terminal are converted to voltage signals, amplified, and output to the output terminal; and one of the above-mentioned input parts is made effective and the other input parts are made ineffective in response to first external signals, the impedance of the first input terminal, the second input terminal, and the output terminal of the above-mentioned ineffective input parts becomes high and the output current from the above-mentioned output terminal becomes zero.