1. A two-dimensional spectroradiometer comprising: an optical system which receives light from an object to be measured to form an optical image; a transmittance wavelength variable filter having a spectral transmittance characteristic that a transmittance wavelength of the light differs depending on a transmittance site of the transmittance wavelength variable filter where the light is passed; a scanner which movably holds the transmittance wavelength variable filter on an optical path forming the optical image for sequential scanning at a. plurality of scanning positions; and an image sensor which captures the optical image composed of the light passing through the transmittance wavelength variable filter at each of the scanning positions of the filter to acquire a plurality of images having a different spectral sensitivity among pixels of the image at the each of the scanning positions.