<p>The present invention is a silylating agent of formula (CH3)(R)(R<1>)SiX ; where R is an isoproply group, R<1> is a monovalent hydrocarbon group having 2 to 6 carbon atoms, and X in a chlorine atom or bromine atom. The silylating agent of the present invention provide silylation product which is much more stable than the silylation product obtained with trimethylchlorosilane, and its protective group is as stable as the silylation product obtained from t-butyldimethylchlorosilane. Moreover, the present described silylating agents are characterized by an easier desilylation than the t-butyldimethylsilyl group.</p>