4-(1-Adamantyl)-3-butenyltriethoxysilane was synthesized from 1-adamantanecarboxylic acid and 3-chloropropyltriethoxysilane. The hydrolysis of this compound in 1-propanol with H2O in the presence of a catalytic amount of nitric acid was conducted by heating to obtain the precursor solution. A glass substrate was coated using this solution, followed by heat treatment at 200°C. The resulting coating film was dense and had no cracks from SEM observation. Thickness, pencil hardness and contact angle with water of the specimen were measured. It was confirmed from these experiments that the adamantyl group was very effective on the coating film in the increase in thickness and improvement of hardness. Its water repellent performance was similar to that of the methyl group. A suspension solution was prepared by adding silicon carbide particles to the precursor solution. Preparation of the coating film using this solution was performed to give a relatively hard, water repellent composite film including particles.