A holey fiber, which has a zero-dispersion wavelength of less than 700 nm and operates as single mode under its zero-dispersion wavelength, is provided. The holey fiber according to the present invention comprises a core region that is formed at a center of the holey fiber; and a cladding region, formed at the circumference of the core region, which has a plurality of holes distributed as triangle lattice around the core region; wherein the holey fiber has a fundamental mode of less than 700 nm, a higher order mode, and the fundamental mode and the higher order mode confinement losses of less than 0.1 dB/m and more than 10 dB/m, respectively, at the zero-dispersion wavelength.