An ultraviolet ray protection agent including a compound having an ultraviolet ray protection effect as an active ingredient. The compound is expressed by general formula I': ##STR00001## wherein X represents NH or O; Y' represents a vinyl group substituted by a methyl group or a phenyl group, or a phenyl group substituted by a methoxy group or a fluorine atom, or a naphthyl group; and Z represents a phenyl group substituted by a methyl group, a carboxyl group or a nitro group, or a naphthyl group. The compound represented by the general formula I' includes both novel compounds of the present invention and known compounds. The ultraviolet ray protection agent of the present invention offers outstanding ultraviolet ray protection effectiveness and is very safe.