A three-dimensional photonic crystal includes a first region including a
first layer, a second layer, a third layer, a fourth layer and a second
region including the first layer, the second layer, the third layer, the
fourth layer, and additional layers including discrete structures spaced
from each other. The horizontal interval and the vertical interval of the
rod-shaped structures in the first region are the same as those of the
rod-shaped structures in the second region, respectively.