The invention provides an objective lens and an optical pick-up device. It is characterized in that the objective lens is a hybrid objective lens which adopts the first, second and third rays with wavelengths of lambda 1, lambda2 and lambda 3 (lambda 2 is greater than lambda1 but less than lambda3) to respectively, regeneratively record on the first, second and third optical information record medium respectively having the first, second and third protective substrates with the thicknesses of t1, t2 and t3 (t2 is not less than t1 but not more than t3). The hybrid objective lens is composed ofa refractive lens and a diffractive optical element constructed by plural coaxial ring-shaped zones on at least one optical surface thereof and configured on beam incident plane of the refractive lens. When n1, n2 and n3 each is a diffraction order of a diffracted ray having a maximum light amount among diffracted rays, and when numerical apertures corresponding to each medium are respectively NA1, NA2 and NA3, if FORMULA and FORMULA, the n1-th, n2-th and n3-th diffracted rays of the first, second and third has an appropriate wavefront within respective numerical aperture NA1, NA2 and NA3.