to optional direction x on a plane perpendicular to an optical axis laminated alternately with a u00bd wavelength plate and a glass base board between it is possible to correct fluctuations of spherical aberration generated in the light converging optical system by impressing voltage on each of the liquid crystal element 1 and the liquid crystal element 2 and thereby by controlling independently x direction component and y direction component of the phase of wave front which transmit the liquid crystal element representing a refractive index distribution changeable element incidentally the refractive index distribution changeable element has only to be one that can form the refractive index distribution which is almost symmetric about an optical axis and it is not limited to the form stated above in fig2 an aspherical single objective lens of the invention having large na and excellent image height characteristics is used as objective lens 8 in the same way as in fig1 and a light source whose wavelength u03bb is as short as about 400 nm is used as light source 1 therefore high density recording and reproducing are possible and a working distance between objective lens 8 and protective layer 9 of the optical information recording.