Provided is a core-shell structure which exhibits excellent fast-acting properties in terms of percutaneous absorption of an active ingredient. A core-shell structure which is provided with a core part that contains an active ingredient and a shell part that contains a surfactant having an HLB value of 4-14. The core part is a solid； and the surfactant has a saturated hydrocarbon group having 7-15 carbon atoms or an unsaturated hydrocarbon group having 7-17 carbon atoms.
