PURPOSE: To obtain the subject composition exhibiting excellent anticorrosive properties in coating on marine vessel or bridge, etc., containing specific ratio of hydrolyzed solution of alkylsilicate, polyvinyl butyral, zinc dust and powdery fatty acid nitrogen derivative compound.

CONSTITUTION: The aimed composition is composed of (A) hydrolyzed solution of alkylsilicate and (B) solution component containing vinyl butyral, (C) zinc dust and (D) powdery fatty acid nitrogen derivative compound. Solid component ratio of SiO2 of the component A and the component B is 97:3-80:20 and the component D is 0.3-3.0wt.% of 100wt.% the composition.