A snapshot spectro-polarimeter comprising: a first linear polarizer configured to linearly-polarize light emitted from a light source; an integrated polarization interferometer, configured to polarization-modulate complex waves that are output from the first linear polarizer and pass through, or are reflected by, an object; a second linear polarizer configured to cause two waves output from the integrated polarization interferometer to interfere with each other; and a measurement device configured to measure spectrum polarization information of light output from the second linear polarizer; wherein the integrated polarization interferometer comprises: a polarizing beam splitter configured to split incident complex waves; a first mirror attached to a first surface of the polarizing beam splitter and configured to reflect, to the polarizing beam splitter, first polarized light passing through the polarizing beam splitter; and a second mirror attached to a second surface of the polarizing beam splitter and configured to reflect, to the polarizing beam splitter, second polarized light reflected by the polarizing beam splitter; and wherein an optical path length of the first polarized light differs from an optical path length of the second polarized light in the integrated polarization interferometer by an attachment interval between the first surface of the polarizing beam splitter and the first mirror differing from an attachment interval between the second surface of the polarizing beam splitter and the second mirror; and wherein the path length difference ranges from 20 μm to 60 μm for an ultraviolet or visible light region and 60 μm to 500 μm for a near-infrared or infrared region. a first linear polarizer configured to linearly-polarize light emitted from a light source; an integrated polarization interferometer, configured to polarization-modulate complex waves that are output from the first linear polarizer and pass through, or are reflected by, an object; a second linear polarizer configured to cause two waves output from the integrated polarization interferometer to interfere with each other; and a measurement device configured to measure spectrum polarization information of light output from the second linear polarizer; wherein the integrated polarization interferometer comprises: a polarizing beam splitter configured to split incident complex waves; a first mirror attached to a first surface of the polarizing beam splitter and configured to reflect, to the polarizing beam splitter, first polarized light passing through the polarizing beam splitter; and a second mirror attached to a second surface of the polarizing beam splitter and configured to reflect, to the polarizing beam splitter, second polarized light reflected by the polarizing beam splitter; and wherein an optical path length of the first polarized light differs from an optical path length of the second polarized light in the integrated polarization interferometer by an attachment interval between the first surface of the polarizing beam splitter and the first mirror differing from an attachment interval between the second surface of the polarizing beam splitter and the second mirror; and wherein the path length difference ranges from 20 μm to 60 μm for an ultraviolet or visible light region and 60 μm to 500 μm for a near-infrared or infrared region. a polarizing beam splitter configured to split incident complex waves; a first mirror attached to a first surface of the polarizing beam splitter and configured to reflect, to the polarizing beam splitter, first polarized light passing through the polarizing beam splitter; and a second mirror attached to a second surface of the polarizing beam splitter and configured to reflect, to the polarizing beam splitter, second polarized light reflected by the polarizing beam splitter; and wherein an optical path length of the first polarized light differs from an optical path length of the second polarized light in the integrated polarization interferometer by an attachment interval between the first surface of the polarizing beam splitter and the first mirror differing from an attachment interval between the second surface of the polarizing beam splitter and the second mirror; and wherein the path length difference ranges from 20 μm to 60 μm for an ultraviolet or visible light region and 60 μm to 500 μm for a near-infrared or infrared region.