Systems and techniques are disclosed to provide a sensor unit configured to sense a living body within a vehicle and to control the vehicle according to the sensed data. A sensor unit is configured to sense infrared light emitted from one or more areas inside the vehicle. A blocking unit is located between the sensor unit and the one or more areas inside the vehicle. A controller is configured to control at least one of the blocking unit or the sensor unit so as to vary an amount of infrared light that the sensor unit is able to receive through the blocking unit from the one or more areas inside the vehicle. The controller determines, based on a variation in the amount of infrared light received by the sensor unit, whether or not a living body is present inside the vehicle.