Object lens for being compatible with optical recording media with different thicknesses

One kind of an objective lens compatible with different thicknesses of the optical recording medium, the light emitted from the light source focused on the information recording surface of the optical recording medium, the objective lens with its optical axis having a constant width provided with an annular phase shift region, and zone through the objective lens is divided into an inner zone and an outer zone, located between the annular inner and outer regions so that the phase shift region of the phase shift of light transmitted through the objective lens of the light passing region, said annular zone having the same phase shift of the objective lens surface surface curvature.