At least one exemplary embodiment is directed to a method for fabricating a three-dimensional photonic crystal. In the method for fabricating the three-dimensional photonic crystal, a plurality of layers can be defined as one unit, and the total thickness of the one unit can be controlled such that an average layer-thickness of the plurality of layers in the one unit is about equal to the ideal layer-thickness so that a photonic band-gap occurs in a desired wavelength region.