Apparatuses and methods are provided which suppress a surge component occurring at an optical amplifier on an optical path through which an optical burst signal is transmitted. An optical amplifier may experience a surge due to the power variation of the optical burst signal that is fed to the optical amplifier. To suppress such a surge component, a power corresponding to a number of wavelengths of an optical burst signal to be input is calculated. The optical amplifier is instructed to generate an optical signal with a power corresponding to a difference between a set value and the calculated power. The generated optical signal and the optical burst signal to be input are coupled and output according to the instruction. Thus, the optical amplifier can receive the optical signal with the constant power and the surge component at the optical amplifier can be suppressed.