PURPOSE: To provide an anti-suntan cosmetic or a medicine for external application so designed as to release an agent such as a ultraviolet light absorber into the preparation only when needed through its release in response to ultraviolet does, leading to the sustainability of the effect of the agent and safety, etc.

CONSTITUTION: Firstly, a polymer containing a triphenylmethane-based compound to be made into an ion through dissociation by ultraviolet light irradiation is synthesized and microcapsules with this polymer constituting the wall membrane are prepared. For the microcapsules, ultraviolet light irradiation will enlarge the pores of the wall membrane or greatly change its polarity, thus effecting raising the permeability of an agent contained therein. The objective cosmetic or the medicine for external application can be obtained by containing a ultraviolet light absorber or anti-inflamm atory agent in such microcapsules. In said cosmetic, the ultraviolet light absorber will be released into the preparation in response to ultraviolet light irradiation; whereas, in the case of no exposure to ultraviolet light, the agent will not be released, thus being favorable in terms of activity, efficacy and safety.