It is an exemplary object of the present invention to provide an aberration measuring apparatus capable of measuring wavefront aberration of an optical system to be analyzed at a high degree of accuracy for a long time. In order to attain this object, the aberration measuring apparatus of the present invention comprises a light source which emits light having a near-infrared wavelength, a wavelength transformer which transforms light from the light source to light having substantially the same wavelength as the wavelength used and an interferometer which causes the light from the wavelength transformer to enter the optical system to be analyzed and measures aberration of the optical system to be analyzed.