A composite photonic structure element includes a photonic crystal and a multi-layer film. The photonic crystal is formed by alternately laying an active layer having a nonlinear effect for converting a fundamental wave into a second higher harmonic and an inactive layer having no nonlinear effect, so that the energy of the fundamental wave coincides with the photonic band gap end. The multi-layer film is formed by layering a plurality of sets of two types of thin films having different refractive indexes so as to reflect the fundamental wave. The multi-layer film is connected to both ends of the photonic crystal. The fundamental wave comes into one of the end faces and the fundamental wave is reciprocally reflected between resonators having a multi-layer film so that the intensity of the fundamental wave in the photonic crystal is increased. The fundamental wave is converted into a second higher harmonic in the active layer and the second higher harmonic is extracted outside from the other end face.