The purpose of the present study was to estimate the minimal food cost based on the dietary reference intake for Japanese people. For this purpose, we calculated the minimal food cost using mathematical optimization. To calculate a food plan for each age-gender group, 68 mathematical optimization models for each of the food plan groups were employed. For the calculation of mathematical optimization models, we used data based on the dietary reference intake for Japanese people and a retail price survey by the Statistics Bureau of the Japanese Government. We established four categories (25％, 50％, 75％ and 85％ for standard food intake). From these restrictions, we calculated the minimal food cost using mathematical optimization. The normal food cost per month for adult males (18-29 years) was 41,865 Yen, and for adult females (18-29 years) was 26,037 Yen. Based on these results, we were able to estimate the minimal food cost for families in order to prevent lifestyle related diseases. In this study we used computed ingredients instead of food to calculate optimal combinations, so it has not been verified whether these combinations can be realized in practice. In order to put the results of this study into practice, it is necessary to verify the results of the calculation and the connection between cooking and menu planning.