Disclosed is a spectrum measuring apparatus for shortening such a measurement time period for an object being measured including two or more mutually different measurement portions as is required for the spectrum measurements of the lights from individual measurement portions. The spectrum measuring apparatus comprises a slit group having two or more slits, a spectroscope for separating the lights extracted by the slit group, for the individual slits, and a measuring unit for measuring the intensities of the individual components, which are separated by the spectroscope, for the slits. The individual slits extract such ones of the lights coming from an object being measured including two or more mutually different measurement portions, as come from the individual measurement portions.