The object of the invention is to provide an infrared circular dichroism measuring apparatus that improves the measuring time and the measuring accuracy.An infrared circular dichroism measuring apparatus 101 comprising: AC signal extractors 110 112 where an interference light beam from an IR light source 102 which has passed an interferometer 103 is converted into a clockwise and a counterclockwise circularly polarized light beams and is irradiated on a sample to extract from a detected signal of detector 107 an interferogram by each of the circularly polarized light beams; DC signal extractors 113, 112 for extracting an interferogram by the IR absorption of the sample; a calculator 114 for figuring out the circular dichroism; and a selective transmitter 120 for narrowing down the wavelength region to be measured based on an IR absorption wavelength region corresponding to a vibration mode of the structure to be measured in the sample molecule.
