The Mekong delta is experiencing flood damage at a time when the population is growing and farmland is expanding. Because the Mekong River Delta is one of the important grain belts in Vietnam, planning disaster mitigation is government policy. The purposes of this study are to present a method of visualizing flooded areas, classify geomorphology, and make flood risk map using JERS-1 SAR of the Mekong River Delta. JERS 1 SAR data, including geo-reference, noise reduction, re-sampling, and calculation of Normalized Radar Cross Section (NRCS), were processed by TNTmips. The flooded area in the Mekong River Delta is visualized and flood dynamics are discussed. The relation between NRCS and micro-geomorphology was clarified by a field investigation and a geomorphologic land classification map is presented. After evaluating flood risk in four levels, a flood risk map was created by visualizing the evaluation. Differences between NRCS of JERS 1 SAR before and after a flood are calculated, and the flooded area is visualized for differences lower than - 1.8 (dB). This value (-1.8 dB) was defined by a field investigation. Flooded area maps for 1995, 1997, and 1998 were created. The relation between NRCS and geomorphology was clarified by field investigations, and a detailed geomorphologic map in the Mekong delta was created with reference to the geomorphologic land classification map.