To provide an optical characteristic measuring device capable of measuring highly accurately, for example, a fine wavy component of a transmission wave front from an optical system or an optical component.

This measuring device is equipped with an interference system 1, 2, 3, 4 for generating the first light flux and the second light flux having an optical path length different from that of the first light flux, and allowing the first light flux to interfere with the second light flux; and a detection system 5, 15 for detecting optical characteristics (a transmission wave front, a refractive index distribution or the like) of a specimen based on an interference fringe formed by interference between the first light flux and the second light flux.