IN-VEHICLE ABNORMALITY DETECTION DEVICE AND IN-VEHICLE ABNORMALITY DETECTION METHOD

A change rate of in-vehicle carbon dioxide concentration at an optional time point when the vehicle is in a parked state is estimated on the basis of detection signals of a COconcentration sensor at two different time points when in the parked state; and on the basis of a detection signal of the COconcentration sensor at the optional time point, a preset time constant of concentration change of the in-vehicle carbon dioxide concentration, and the estimated change rate, the in-vehicle carbon dioxide concentration at a time point when a predetermined time according to the time constant has elapsed since the optional time point is estimated (steps S to S). A detection target organism is determined to be present in the vehicle when the estimated in-vehicle carbon dioxide concentration is equal to or more than a threshold value set according to the detection target organism (steps S and S).