A one-pack type of curable composition comprising a blend consisting essentially of a silyl group containing resin having a backbone substantially comprising a vinyl type polymer chain and containing at least one silicon atom attached to a hydrolyzable group at a terminal or in a side chain of its molecule, a curing catalyst, and a solvent. This composition has excellent storage stability, excellent workability, excellent weather resistance, and excellent weather resistance after coating and curing, and high hardness of the coated surface after curing.