In a light transmission apparatus which controls an optical excitation intensity of an amplifying optical fiber or an attenuation of an optical variable attenuator based on an output light intensity, the output light intensity is sampled. When a change rate of an input light intensity exceeds a threshold value, the optical excitation intensity or the attenuation is controlled based on the output light intensity immediately before the change rate exceeds the threshold value. Accordingly, an occurrence of an optical surge is prevented and it is made possible to output an optical signal free from a signal error or a signal disconnected state.