A conventional broadband quarter-wave plate has not completely solved the wavelength dependence and has different efficiencies of shifting the phase by 90.degree. depending on the wavelengths, and therefore has a problem that it cannot fulfill the strict specifications on the optical characteristics which are demanded of a wave plate from a viewpoint of the optical efficiency and the like in an optical pickup device compatible with a plurality of different wavelengths. To provide a wave plate which completely functions as a quarter-wave plate with respect to a plurality of different wavelengths and an optical pickup using that wave plate to solve the problem, the present invention provides a laminated wave plate, wherein a wave plate with a phase difference .alpha. and a wave plate with a phase difference .beta. with respect to monochromatic light with a wavelength .lamda. are laminated in such a way that directions of optical axes of said plates intersect each other, so that the laminated wave plate, as a whole, functions as a quarter-wave plate, and which is characterized in that a relationship between the .alpha. and the .beta. satisfies the following formulas: (3/2).times..pi..noteq..alpha.-2.times..pi..times.(m-1) .pi..noteq..beta.-2.times..pi..times.(n-1), wherein: each of m and n is a positive integer.