Raman amplifier and raman amplifier adjustment method

A Raman amplifier amplifying multiple-wavelength light with the use of a fiber connecting medium, comprising;

• a pumping unit supplying pumping light to the fiber connecting medium;
• a light monitoring unit detecting light power of the multiple-wavelength light;
• a noise measurement unit measuring ASS noise during the output of an optical amplifier provided in an upstream station with respect to the fiber connecting medium being stopped;
• a deriving unit deriving a Raman gain in the fiber connecting medium based on the thus-measured ASS noise;
• and
• a determination unit determining power of the pumping light to be supplied based on the light power detected by said light monitoring unit and the Raman gain derived by said deriving unit.