The objective optical system, optical pickup device, and optical disk drive device

The present invention is, for the first optical information recording medium for at least the protective substrate thickness t1, reproducing and / or recording information by using the first light flux of the first wavelength λ1 emitted from the first light source, the protective substrate the third optical information recording medium of thickness t3 (t1 optical pickup apparatus, an objective optical system having at least a first optical element, the first optical element, stacked in the optical axis direction, and the second consisting of a first member and a material B made of a material a and a member, said material B and the material a is the Abbe number different from each other at the d-line, the first member and the boundary surface of the second member objective optical system first phase structure is formed, the the optical pickup apparatus mounted with the objective optical system, and Hikaride To provide a disk drive device.