Scattering can be measured by using an optical system having a Hartman-Shack wave-surface sensor. An eye optical characteristic measuring instrument comprises a light source unit 10 for emitting a light beam of a wavelength in the near-infrared region, an illumination optical system 40 for illuminating a small area of the retinal of an eye to be measured with the light beam from the light source unit 10, a light-receiving optical system 20 for receiving a part of the reflected beam of the light beam from the light source unit 10 reflected from the retina through a converting member for converting the part of the reflected light beam into at least substantially 17 light beams, a light-receiving section 23 for receiving the received light beam directed by the light-receiving optical system 20 and generating a signal, and a calculating unit for determining the wavefront aberration of the light beam entering the light-receiving optical system 20 and the degree of scattering of the received light beam on the basis of the signal from the light-receiving section 23.