A spectral characteristic measuring device comprising a spectrometer and a control device, wherein said spectrometer includes, a light shielding body provided with an opening, a light receiving unit in which a plurality of light receiving elements are arrayed in a direction along one axis and that outputs a signal from each of said light receiving elements according to an irradiation light quantity, and an optical system that disperses the light passed through said opening according to a wavelength to form a dispersion image on said light receiving unit; and said control device includes, a storage unit for storing wavelength information indicating a correspondence relationship between said plurality of light receiving elements and wavelengths of piece of lights irradiated on said plurality of light receiving elements, an intensity distribution acquiring portion for acquiring a first intensity distribution related to a first dispersion image and a second intensity distribution related to a second dispersion image based on the signal outputted from each of said light receiving elements when a monochromatic light is passed through said opening and said first dispersion image related to a primary diffracted light and said second dispersion image related to a secondary diffracted light are formed on said light receiving unit, characterized by a first calculation portion for calculating an estimated intensity distribution related to said second dispersion image from said first intensity distribution according to a predetermined relational expression, a second calculation portion for calculating a wavelength change amount related to said wavelength information corresponding to a shift amount between said estimated intensity distribution and said second intensity distribution with respect to a direction along said one axis by a comparison of said estimated intensity distribution and said second intensity distribution while relatively moving at least one of said estimated intensity distribution and said second intensity distribution in a direction along an axis corresponding to a direction along said one axis, and a correction portion for correcting said wavelength information according to said wavelength change amount; wherein said plurality of light receiving elements include a first light receiving element group to be formed with said first dispersion image and a second light receiving element group to be formed with said second dispersion image, and said predetermined relational expression includes a first portion for calculating a temporary intensity distribution related to said second dispersion image from said first intensity distribution according to an association degree between each intensity component of said first intensity distribution and each intensity component of said second intensity distribution, and a second portion for calculating said estimated intensity distribution from said temporary intensity distribution while reflecting a difference in efficiency from said passing of the light at said opening to the output of the signal by each light receiving element between said first light receiving element group and said second light receiving element group.