A two-dimensional photonic crystal plane emission laser of the invention includes a two-dimensional photonic crystal which has a two-dimensional photonic crystal area and a light reflecting area, and which selects a wavelength of light to be generated in an active layer. The light reflecting area is formed in such a manner that when light leaking from the two-dimensional photonic crystal area and reflected on a reflecting surface of the light reflecting area is returned to the two-dimensional photonic crystal area, the reflection light is combined with a standing wave residing in a propagating direction of the reflection light without disturbing its resonant state.