PURPOSE: To provide uniform coating by directly coating a portion which is in contact with the air of high humidity on the interior material surface with a anti-microorganism treating agent for disinfection and deodorization.

CONSTITUTION: After tiling, painting and other work of interior are completed, the contamination of surface is decomposed and removed, deodorizing treatment is done, and the surface of the object being treated is cleaned with water or the like. Then, the coating for disinfection and deodorization is performed on the surface of the object being treated. At this time, a hydration condensation reaction of Si-QAC with the surface of the object being treated occurs. In this reaction, the molecules of Si-QAC are bonded to form a strong film on the surface of interior material. This method provides uniform film.