The purpose of this study is to minimize the PCH(Propylene CHlorohydrins) as a by-product in HPMC(HydroxyPropyl MethylCellulose) manufacturing process. HPMC is made of cellulose which is natural high polymer. And HPMC is applicable to several industrial areas. Especially it can be used in food industry as an effective additive. PCH is the by-product which is generated in chemical reaction in HPMC manufacturing process. So it is essential to eliminate PCH for the improvement of product quality. Therefore we have studied to minimize the amount of PCH. It is expected that the application of HPMC could be enlarged as the result of this study.