Developing carbohydrate fat replacer as materials for low-calorie and low-fat food made of Korean potato, it is expected that the new demand of fat replacer will be created. Potato starch was modified by chemical modification. Observing modified starch(treated in different method) by SEM, EZ(treated by enzyme) showed shape of deformed round oval, AC(treated by acetylation,), HPR(treated by hydropropylation) showed shape similar to that of NL(N-Lite), the commercial fat replacer. In the modified starch such as AC, peak in B and C type similar to those of general starch was found, but EZ showed non-crystalline shape. Compared to other modified starch, HPR, the chemically produced denatured starch showed very peculiar peak and structure in V-form. While the order of contents of amylopectin was in the order HPR > EZ > AC showed extremely high contents. Measuring the degree of gelatinization per the modified method, the degree of gelatinization of HPR as much higher than others. The water binding activity of modified starch was 240% in HPR. Measuring viscosity by producing general starch and modified starch as gel of 10% concentration, the CPS showed very high viscosity of 30.30 ${ imes}$ 10$^3$ cp. Showing viscosity of 38.60, 31.60 10$^3$ ${ imes}$ cp, the modified starch was in the order of HPR. While the calorie of starch of GPS was measured to be 3.0 Kcal/g, very low calorie those of chemically modified starch, HPR showed 2.5 Kcal/g respectively, suggesting that calorie is decreased by modified treatment. The appropriateness of processing food was experimented by substituting the existing oil and fat containing food with saturated gel of starch and modified starch in constant rate through utilization of modified starch. Therefore, research and development for materials and related products which maintain the existing quality and reduce fat contents will be constantly performed in the future.