PROVIDED IS A NOVEL COMPOUND WHICH HAS EXCELLENT ULTRAVIOLET-ABSORBING FUNCTION (ESPECIALLY UVA ABSORBING FUNCTION) AND EXCELLENT HYDROPHILICITY. A BENZYLIDENE AZOLIDINE DERIVATIVE OF THE PRESENT INVENTION OR A SALT THEREOF IS CHARACTERIZED BY BEING A BENZYLIDENE AZOLIDINE DERIVATIVE REPRESENTED BY SPECIFIC STRUCTURAL FORMULA (I) OR A SALT THEREOF. (IN STRUCTURAL FORMULA (I), N REPRESENTS AN INTEGER OF 1-5； A1 REPRESENTS O, S OR N-A4 AND EACH OF A2, A3 AND A4 INDEPENDENTLY REPRESENTS A HYDROGEN ATOM, AN ALKYL GROUP WHICH MAY BE SUBSTITUTED BY A HYDROXYL GROUP AND HAS 1-8 CARBON ATOMS, OR THE LIKE (PROVIDED THAT AT LEAST ONE OF A2, A3 AND A4 CONTAINS ONE OR MORE HYDROXYL GROUPS). IN THIS CONNECTION, WHEN N IS AN INTEGER OF 2-5, THE PLURALITY OF A3O— MOIETIES MAY BE THE SAME AS OR DIFFERENT FROM EACH OTHER.)
