Provided is a novel metal oxide. Specifically provided is a metal oxide having a plurality of energy gaps, wherein the metal oxide is provided with a first layer in which the energy level at the bottom of the conduction band of the energy band is high and a second layer in which the energy level at the bottom of the conduction band of the energy band is lower than that of the first layer, the second layer has more carriers than the first layer, the difference between the energy levels at the bottom of the conduction band in the first layer and the second layer is at least 0.2 eV, and the first layer and the second layer are alternately layered.
