The present invention intends to provide a two-dimensional photonic crystal resonator having a high Q-value. The slab-shaped body 21 is provided with cyclically arranged holes 22. The body 21 is divided into three areas 31-33 with the holes 22 arranged with cycle distances of a1 in area 31 and a2 in areas 32 and 33, which is smaller than a1. A waveguide 23 passing through the three areas is formed by linearly eliminating the holes 22. The waveguide 23 thus formed can propagate rays of light within a wavelength band that depends on the cycle distance of the holes 22. The cycle distance of the holes in the area 31 differs from that of the areas 32 and 33, and the wavelength band of the light propagating through the waveguide accordingly differs. Therefore, a ray of light whose wavelength is within the waveguide transmission wavelength band of the area 31 but outside of the waveguide transmission wavelength band of the other areas 32 and 33 will be confined within the waveguide of the area 31 and resonate therein. Thus, the waveguide in the area 31 functions as a resonator.