A calibration apparatus for calibrating an emission spectroscopy analyzer that monitors plasma generated in a plasma processing apparatus. The calibration apparatus comprises a base substrate; a plurality of light emitting devices disposed on the base substrate, each light emitting device of the plurality of light emitting devices is configured to emit light having different wavelengths from other light emitting devices of the plurality of light emitting devices; a reflector disposed on the base substrate, the reflector configured to reflect the light emitted by the plurality of light emitting devices toward an outside of the base substrate in a plan view; and a control device disposed on the base substrate, the control device configured to control the plurality of light emitting devices.