A current detection circuit detects photoelectric current that flows through a phototransistor, and outputs a current, which is proportional to the photoelectric current, via an output terminal. An input-side transistor is a PNP bipolar transistor, and is provided on a current path for the phototransistor. Output-side transistors are PNP bipolar transistors. The base terminals thereof are connected to that of the input-side transistor so as to form a common base terminal, and the emitter terminals thereof are connected to that of the input-side transistor so as to form a common emitter terminal, thereby forming a current mirror circuit. Each of first switches is provided between the collector of the corresponding output-side transistor and an output terminal. Each of second switches is provided between the collector of the corresponding output-side transistor and the ground terminal. A control unit controls the ON/OFF operations of the first switches and the second switches.