A sensor device includes a sensor array in which infrared sensors are arrayed and a detection circuit connected to the output signal line of the sensor array. The detection circuit includes a capacitor having a charging circuit which is selectively driven, a sense amplifier circuit which detects and amplifies a change in sensor current flowing to the output signal line, a current-to-voltage conversion circuit which converts the output current from the sense amplifier circuit into a voltage, a discharging circuit which is controlled by the output voltage of the current-to-voltage conversion circuit to discharge the capacitor, and an output circuit which outputs the terminal voltage of the capacitor.