An objective lens that satisfies conditions:

-0.02f1M10.02  (1)

-0.02f2M20.02  (2)

-0.29f3M3-0.19.  (3)

At least one of lens surfaces of the objective lens includes a diffracting structure having a first region for converging the third light beam on a data recording layer of the third optical disc. The diffracting structure within the first region is configured such that a diffraction order at which diffraction efficiency of the first light beam is maximized is a sixth order, a diffraction order at which the diffraction efficiency of the second light beam is maximized is a fourth order, and a diffraction order at which the diffraction efficiency of the third light beam is maximized is a third order.