There is provided a coating composition capable of improving performance of coated films, such as dirt shedding property and weathering resistance, only by applying directly onto the surface of various structures such as building structures and civil engineering structures or on a previous coating film without requiring formation of any undercoat. A silicon-containing liquid composition having a water concentration of 50% by weight or more and a light transmittance of 70% or more, wherein the silicon-containing liquid composition is a composition capable of forming a film on a substrate having a water contact angle of 60.degree. or more.