An optical amplification apparatus has a first optical amplification unit and a second optical amplification unit connected in tandem with an optical attenuator between them. A temperature sensor is located in the vicinity of an optical fiber included in the second optical amplification unit. A reference voltage generation circuit controls an automatic gain control (AGC) circuit according to an output signal of the temperature sensor Alight signal detector detects maximum or minimum power from among the powers of the wavelength components output from the second optical amplification unit. The AGC adjusts the pumping power to set maximum/minimum to a predetermined value.