Provided are an objective lens with enhanced transmittance and an optical pickup apparatus which can record and/or reproduce information properly for three kinds of discs with different recording densities, even if a single lens is used as the objective lens. When all the expressions (1) to (3) are satisfied, excellent aberration characteristics can be obtained for the three kinds of discs: −0.02≦m1≦0.02 (1); 0≦(WD1−WD2)≦1.57 m2+0.123 or 1.57 m2+0.24≦(WD1−WD2)≦0.7 (2); and 0≦(WD1−WD3)≦1.79 m3+0.333 or 1.66 m3+0.508≦(WD1−WD3)≦0.7 (3).