An in-vehicle radar device comprising: transmission means for emitting an electromagnetic wave; scanning means for horizontally scanning the electromagnetic wave emitted by the transmission means; and reception means for receiving a reflected wave reflected by a target with respect to the electromagnetic wave emitted by the transmission means; wherein the in-vehicle radar device being adapted to detect, based on an elapsed time from when the transmission means emitted the electromagnetic wave until the reception means receives the reflected wave and on the scanning direction of the electromagnetic wave by the scanning means, at least a position and a horizontal width of the target reflecting the electromagnetic wave; and the in-vehicle radar device further comprising: storage means for storing intensity of a previous time or few times before of the reflected wave received by the reception means; and comparing means for comparing the intensity of the reflected wave of the previous time or the few times before stored in the storage means and intensity for this time; characterized in that the in-vehicle radar device further comprises judgment means for judging that the target detected this time differs from a target continuously detected from the previous time or the few times before and the target detected this time is not a leading vehicle but a climbing road if the intensity of the reflected wave for this time suddenly decreased compared to the intensity of the previous time or the few times before, and the horizontal width of the target becomes greater than a horizontal width of a general vehicle. transmission means for emitting an electromagnetic wave; scanning means for horizontally scanning the electromagnetic wave emitted by the transmission means; and reception means for receiving a reflected wave reflected by a target with respect to the electromagnetic wave emitted by the transmission means; wherein the in-vehicle radar device being adapted to detect, based on an elapsed time from when the transmission means emitted the electromagnetic wave until the reception means receives the reflected wave and on the scanning direction of the electromagnetic wave by the scanning means, at least a position and a horizontal width of the target reflecting the electromagnetic wave; and the in-vehicle radar device further comprising: storage means for storing intensity of a previous time or few times before of the reflected wave received by the reception means; and comparing means for comparing the intensity of the reflected wave of the previous time or the few times before stored in the storage means and intensity for this time; characterized in that the in-vehicle radar device further comprises judgment means for judging that the target detected this time differs from a target continuously detected from the previous time or the few times before and the target detected this time is not a leading vehicle but a climbing road if the intensity of the reflected wave for this time suddenly decreased compared to the intensity of the previous time or the few times before, and the horizontal width of the target becomes greater than a horizontal width of a general vehicle. storage means for storing intensity of a previous time or few times before of the reflected wave received by the reception means; and comparing means for comparing the intensity of the reflected wave of the previous time or the few times before stored in the storage means and intensity for this time; characterized in that the in-vehicle radar device further comprises judgment means for judging that the target detected this time differs from a target continuously detected from the previous time or the few times before and the target detected this time is not a leading vehicle but a climbing road if the intensity of the reflected wave for this time suddenly decreased compared to the intensity of the previous time or the few times before, and the horizontal width of the target becomes greater than a horizontal width of a general vehicle.