An optical density changing element comprising: an anode; and a cathode, wherein at least one of the anode and the cathode comprises a first compound that changes a spectral absorption spectrum of the first compound in a wavelength of 400 to 700 nm by providing an electron to or receiving an electron from the at least one of the anode and the cathode, and wherein at least one of the anode and the cathode comprises a second compound that does not change a spectral absorption spectrum of the second compound in a wavelength of 400 to 700 nm by providing an electron to or receiving an electron from the at least one of the anode and the cathode.