Disclosed is a curable composition characterized in that the composition comprises:(i) 100 parts by weight of a polymer mixture of(a) about 5 to about 95% by weight of a polymer (X) containing a specific polysiloxane macromonomer as an essential monomer or a polymer (Y) containing a specific alkoxysilane-containing vinyl monomer as an essential monomer, and(b) about 95 to about 5% by weight of a polymer (Z) containing an epoxy-containing vinyl monomer as an essential monomer; and(ii) about 0.01 to about 30 parts by weight of at least one chelate compound selected from the group consisting of aluminum chelate compound, titanium chelate compound and zirconium chelate compound.