Two optical discs used with a laser light having the same wavelength but having different substrate thicknesses can be handled by a single optical disc apparatus and a multilayer optical disc can also be reproduced. A refractive lens unit and liquid crystal elements are provided so as to condense laser light on an optical disc having a thin substrate thickness with a first NA and to condense laser light on an optical disc having a thick substrate thickness with a second NA smaller than the first NA. The refractive lens unit is designed such that the amount of RMS wavefront aberration is minimized with respect to an intermediate substrate thickness between the two optical discs in the range of the second NA; and the RMS wavefront aberration is 0.05λ or less with respect to the substrate thickness of the optical disc in an area outside the second NA. A liquid crystal element for compatibility corrects spherical aberration due to the difference in substrate thickness between the two optical discs. A liquid crystal element for multilayer corrects spherical aberration based on layer selection of a multilayer optical disc.