In order to allow for easy judgment of performance of optical material having a prescribed function, provided is a transmitted light observation apparatus comprising a light emitting section that generates light including light of a prescribed wavelength; a holding section that holds a first test material and a second test material arranged respectively in optical paths of the light generated by the light emitting section; and a reflecting portion that reflects at least a portion of the light transmitted respectively through the first test material and the second test material. Transmittance of the first test material for the light of the prescribed wavelength is different from transmittance of the second test material for the light of the prescribed wavelength. The light of the prescribed wavelength has a wavelength from 380 nm to 500 nm.