A dimming device is provided by using a material which is capable of transitioning between a metallic reflection state and a transmitting state. The dimming device has a layered structure including a first layer and a second layer, such that the light reflectance of the first layer changes in response to an external stimulation. The first layer contains a first material whose optical characteristics change in accordance with a concentration of a specific element. The second layer contains a second material capable of containing the specific element, the second material releasing or absorbing the specific element in accordance with the external stimulation.