Abstract: Excitation light from a light source is divided into a sample beam and a correction beam by a half mirror, so that the sample beam is converged on a sample in a sample part by convergent lenses. Condenser lenses are provided in order to converge scattered light from the sample on an inlet slit of a spectroscope, and a holographic notch filter which is set to include the wavelength of the excitation light in its notch region is arranged in order to remove the same wavelength component as the excitation light from the scattered light for selecting target light. The target light and the correction beam are guided onto the same optical axis by a half mirror, to be incident upon a polychrometer through the inlet slit and simultaneously detected. The detected value of the target light is corrected by a simultaneously detected intensity of the correction beam.