Structural and optical characteristics in Se thin film fabricated by EBE method had been studied. Se thin film was deposited with noncrystalline until substrate temperature of >$100^{circ}C$ Color of its surface had red genealogy, and its optical energy band gap was about 2.45 eV. But Se film was grown with monoclinic at substrate temperature of over >$150^{circ}C$</TEX> Also, color of its surface had gray genealogy, and its optical energy band gap was about 2.31 eV. Finally, after heat-treatment at >$150^{circ}C$ for 15 min with substrate temperature of >$100^{circ}C$</TEX> noncrystalline Se was proved to be hexagonal, and color of its surface had dark gray genealogy, and its optical energy band gap was about 2.06 eV. From the results, it was known that Se thin film for photoelectric device with the lowest optical energy band gap was accepted from hexagonal structure.