The present invention relates to a main wavelength band of a pump light source capable of improving the pump efficiency while using 1.6 μm fluorescence emitted from Ho3+:5I5→5I7 transition as an optical amplifier, and an assistant pump wavelength band capable of accomplishing population inversion between 5I5 level and 5I7 level to improve the signal gain characteristics of such amplifier. The optical amplifier using optical materials to which holmium or holmium and terbium, holmium and europium, holmium and neodymium or holmium and dysprosium, etc. are doped can be pumped using a light source that emits light of 11,200˜11,500 cm−1 or a light source that emits light of 6,000˜6,500 cm−1.