An electron-beam excitation laser has a laser structure with a light emitter and reflectors on one hand and an electron source on the other hand, wherein at least part of the light emitter or reflectors has a multidimensional photonic crystal structure. An electron-beam excitation laser includes an electron source emitting electrons and a laser structure consisting of a light emitter and reflectors, accelerates electrons from the electron source, and irradiates the electrons to the laser structure to emit a laser beam from the laser structure, wherein the reflectors and/or the light emitter in the laser structure are formed with multidimensional photonic crystals in which dielectrics with different dielectric constants are arrayed in a plurality of directions at periodic intervals, and one of the dielectrics with different dielectric constants may be formed with a light-emitting material.