Photonic crystals are materials which have the novel ability to control optical modes. In this article, we present recent results of light-emission control via the introduction of a photonic crystal into various emitters, including light-emitting diode structures which will become important in future illumination systems. It has been clearly demonstrated that the unusable portion of the light emission can be inhibited by the so-called photonic bandgap, while the emission efficiency in the direction where desired optical modes exist can be enhanced. In addition, the preliminary results of light emission from nitride-based semiconductor photonic crystals are reported.