A curable composition which comprises the following two components: (I) a vinyl polymer having at least one crosslinkable silyl group represented by the general formula (1) given below, and (II) an epoxy resin or a polyether polymer having at least one crosslinkable silyl group; —[Si(R1)2−b(Y)bO]m—Si(R2)3−a(Y)a  (1) {wherein R1 and R2 each represents an alkyl group containing 1 to 20 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an aralkyl group containing 7 to 20 carbon atoms, or a triorganosiloxy group represented by the formula (R′)3SiO— (in which R′ represents a monovalent hydrocarbon group containing 1 to 20 carbon atoms and the three R's may be the same or different) and, when there are two or more R1 or R2 groups, they may be the same or different; Y represents a hydroxy group or a hydrolyzable group and, when there are two or more Y groups, they may be the same or different; a represents 0, 1, 2 or 3; b represents 0, 1 or 2; and m represents an integer of 0 to 19; with the condition that a, b and m satisfy the relation a+mb≧1}.