The photolysis rate of tetramethylsilane (TMS), hexamethyldisilane (HMDS), and trimethylsilane (TrMS) by ArF excimer laser was studied by measuring gas phase IR absorption spectra before and after the irradiation. Decomposition of TMS and HMDS obeyed first-order reaction kinetics and the reaction rate constants of both were proportional to 1.6 power of the laser fluence. Detected gaseous decomposition products by IR spectroscopy of TMS were TrMS and CH4, and those of HMDS were TMS, TrMS, and CH4. Decomposition rate constant of HMDS were two order of magnitude larger than that of TMS. TrMS, which has little absorption at the wavelength of ArF laser radiation, were also decomposed by ArF laser especially in case TMS coexists in the ambient and it was implied that sensitized reaction was involved in decomposition process of TrMS. SiC film was obtained by decomposition of HMDS.