This study was examined closely physiological activation and intended to present the possibility of developing food low-fat food. Developing carbohydrate fat replacer as materials for low-fat food made of Korean potato starch, it is expected that the new demand of fat replacer will be created. Potato starch was modified by chemical modification. The calorie of starch of GPS was measured to be 3.0 kcal/g, 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 gel of starch and modified starch in constant rate through utilization of modified starch. When producing mayonnaise by substituting edible oil with gel of modified starch in 10-50%, calorie was reduced by 44${sim}$45% when substituted by 50%, suggesting the potential of low-fat food. Measuring viscosity of mayonnaise by Brookfield viscometer, the mayonnaise with HPR showed high viscosity and the chemical modified starch group of EZ also showed high viscosity. Generally, the material property of mayonnaise tended to reduce in all measured items when oil and fat are substituted by starch substituting materials and the substituting materials increase. When it comes to the emulsification stability of mayonnaise with starch substituting materials, emulsification stability of all mayonnaise with starch substituting materials is lower than that of compared group. While the group with NL as commercial fat replacer showed emulsification stability which was slightly higher than group with modified starch and the substitution group of HPR showed higher emulsification stability. Sensory evaluation for low-fat mayonnaise by substituting oil the products substituted by modified starch was more preferred than general starch substituting products such as GPS. While NL as commercially fat replacer showed the hight preference, products with H40, EZ were also highly preferred.