An optical pickup apparatus comprising: a first, second and third light sources emitting first, second and third light flux having first wavelength of λ1, second wavelength of λ2 and third wavelength of λ3, respectively; and an objective optical system converging the first, second and third light fluxes onto an information recording surface of a first, second and third optical disk, respectively, wherein the objective optical system has a phase structure, and wherein when a first, second and third magnifications of the objective optical system for conducting reproducing information from and/or recording information on the first, second and third optical disks are represented by M1, M2, and M3, respectively, |dM1−M2|, which represents an absolute value of a difference between M1 and M2, satisfies the following relation. |dM1−M2|