The purpose of the present invention is to make a false positive detection of a target unlikely. This infrared detection device (C1) is provided with an infrared sensor (32) and a mirror (4). The infrared sensor (32) receives infrared rays. The mirror (4) condenses the infrared rays onto a light receiving surface (32a) of the infrared sensor (32). The mirror (4) is provided with multiple reflector mirrors (4a-4h) and a mounting platform (41). The multiple reflector mirrors (4a-4h) define mutually different detection ranges. The multiple reflector mirrors (4a-4h) are provided on the mounting platform (41). Further, the mounting platform (41) has separating walls (41a) that separate the multiple reflector mirrors (4a-4h) that are adjacent to one another.
