In an integration mode, since a switch becomes OFF, a positive feedback path from an output terminal of an operational amplifier to a positive input terminal is blocked. Therefore, oscillation can be prevented even when a voltage of a signal line connected to a reference voltage supply point varies due to an impedance of the reference voltage supply point not being 0. In the integration mode, a resistor and a capacitor function as a noise filter. Further, in a reset mode, a switch becomes ON, and charge is accumulated in the capacitor depending on a reference voltage of the reference voltage supply point.