The present invention provides an inexpensive retardation optical element having the function of reflecting ultraviolet light, capable of decreasing the amount of ultraviolet light that enters a liquid crystal cell, and a liquid crystal display comprising such a retardation optical element. A retardation optical element having the function of reflecting ultraviolet light 10 comprises a retardation layer 12 having a cholesteric liquid crystalline molecular structure in planar orientation. The retardation layer 12 is made so that at least part of its selective reflection wave range for light, which the retardation layer 12 selectively reflects, due to its liquid crystalline molecular structure, is included in an ultraviolet region of 100 to 400 nm and that the maximum reflectance for light in this ultraviolet region is 30% or more.