To provide an optical nanofiber resonator having an optical waveguide whose diameter is equal to or smaller than the wavelength of a propagation light, a light emitter disposed at a predetermined position of the optical waveguide, and a first reflector and a second reflector formed in the optical waveguide with the light emitter interposed therebetween, wherein at least one of the first reflector and the second reflector transmits a part of the propagation light. With such a configuration, the channeling efficiency of the light emitted from the light emitter and the propagation mode of the optical waveguide is dramatically improved.