CORE-SHELL STRUCTURE, PREPARATION, MEDICINE FOR EXTERNAL APPLICATION, TAPE AGENT AND COSMETIC PRODUCT Provided is a core-shell structure having an excellent immediate effect in transdermal absorption of an active ingredient. A core-shell structure comprising a core portion containing an active ingredient, and a shell portion containing a surfactant having an HLB value of 4 to 14, the core portion being solid, and the surfactant containing a saturated hydrocarbon group having 7 to 15 carbon atoms or an unsaturated hydrocarbon group having 7 to 17 carbon atoms.
