This study investigated on an optimum operational condition for the removal of Natural Organic Matters (NOM) by coagulation or coagulation-microfiltration(MF). It was done by the analysis of the water quality of nautral river water before and after the treatment in terms of zeta potential, turbidity, CODMB DOC and UV254. The coagulants used in the experiments were PAC, Alum, and FeCl3. The removal of NOM was also investgated by floating-media(FM)-sand filtration process and the result was compared with that by the coagulation-MF process. In the case of coagulation-MF process, FeCl3 showed the highest organic matters` removal of 76.4% and, Alum and PAC removed 63.9% and 59.9%, respectively. The comparison of the result by FM-sand filtration process were as follows. The removals of CODMn by the coagulation-MF and FM-sand filtration were 78% and 51% the removals of UV254 were 76% and 52%, and the removals of turbidity were 99% and 87% respectively. This result showed the removal by the MF process was higher than that by FM-sand filtration process.