Use of .delta.-tocopherol for enhancing the heat stability and/or oxidation stability of a para-methoxycinnamic ester; an ultraviolet absorber comprising a para-methoxycinnamic ester, and an effective amount of .delta.-tocopherol to enhance its heat stability and/or oxidation stability; and a cosmetic comprising the above ultraviolet absorber..delta.-tocopherol enhances the heat stability and/or oxidation stability of the para-methoxycinnamic ester which is an ultraviolet-absorbing substance frequently used.