An object of the present invention is to solve the problems in conventional art antigen exposure chambers, and specifically, to provide an antigen exposure chamber system capable of simultaneously exposing a large number of test objects in a chamber to a uniform antigen (pollen, mite or house dust, etc.) in all seasons. In order to achieve the above object, in an antigen exposure chamber system according to the present invention, an outdoor air is supplied via an outdoor air diffuser 2 provided in a ceiling surface of an exposure chamber 1 into the exposure chamber from the ceiling surface of the exposure chamber in a horizontal direction, a fan unit 15, including a supply port and a suction port, is provided in each of the four corners of the exposure chamber to provide a circulating flow of air flowing with circulation in the horizontal direction in the exposure chamber, an air exhaust port 4 is provided at a floor surface of the exposure chamber to exhaust an air from the floor surface of the exposure chamber, an antigen is supplied from an antigen supply device to the outdoor air diffuser provided on the ceiling surface so that the antigen is mixed with the outdoor air, and a uniform concentration antigen exposure is enabled by the circulating flow of air.