A curable composition including a fluorine-containing silane compound having two or more Si atoms each bonding to at least one group selected from the group consisting of a hydroxyl group and a hydrolyzable group, an organosilicon compound having at least two —O—Rg3(s) each bonding to a Si atom, wherein each Rg3, at each occurrence, independently represents a hydrogen atom or monovalent organic group, and a metal-based catalyst represented by M(-O—Rh)η, wherein: M represents a metal atom; each Rh, at each occurrence, independently represents a hydrocarbon group having 1 to 3 carbon atoms; and η is the coordination number of M.