According to the doctrine of the five natural elements of the positive and negative, this thesis commits to discuss the traditional food and its dietetic culture of Korea which had deeply influenced the Korean mentality. The article demonstrates this point from the following two aspects: Firstly, the effect of the doctrine of the five natural elements of the positive and negative to the traditional theory of Korean foods. The core of the doctrine of the five natural elements of the positive and negative is to make people adept to the nature through the transform of the positive and negative and the five elements. And the central theory of the Korean traditional cuisine is to "temper", namely to make different mixtures of the staple foods and non-staple foods in accordance with different seasons and different physical status of the persons. Based on this first theory, the women's book gives a stipulation on the quality and taste of the corresponding staple food materials when people take beef, mutton, pork or dogs' meat. Based on the second theory, which stresses the importance of season factors of eating food, the dogs' meat soup in summer and cold noodle that is made of buckwheat flour in winter become a special characteristic of the Korean cuisine; another theory, which is the way of eating different foods according to a person's physical status, set the foundation of the development of the Korean traditional medical theories. In the mean time, this theory of "tempering" has played an important role in the areas of formal cuisine. Either the wine drunk from nuptial cups by the bridegroom and bride on their wedding day or the formulations of the quantity and the eating order of the foods, is following the rule of keeping dietetic balance on the base of the transformation of the positive and negative and five elements of the food, by which to express their blessing for the new couple or their pray for the dead one. Secondly, the effect of the doctrine of the five natural elements of the positive and negative to the color and quantity of the traditional food. According to the doctrine of the five natural elements of the positive and negative, there are only five kinds of color in the world--Qing (blue or green), red, yellow, white and black. In addition to symbolization of the sense of "magnificent and propitious", each of these five colors has its own sense respectively according to the five elements. This is the reason why Korean people stress the symbolic significance of the food. For example, people take black-colored vegetable soup to enrich their blood, and eat red-bean gruel on the 11th lunar month to get rid of the disturbance of evils. Beside this, Korean people strive for visual beauty of their foods by using of the five colors, and even in kimchi, which is eaten each meal. The symbolic sense of the food's quantity combinations is also based on the doctrine of the five natural elements of the positive and negative. According to theory of the positive and negative, odd numbers belong to positive numbers, and symbolize male and strength; according to the theory of the five natural elements, odd numbers which is centered by the number "five" divide the whole cosmos into spaces centered by the "core". This is consistent with the traditional idea of Korean Nation that males take a higher position in the farming society, and the idea of pursuing perfect harmony with the nature. So instead of using even numbers, Korean people rather like to use odd numbers more in their food quantity combinations. This custom is widely used in formal cuisine and special local cuisine, which may be named as "five spicy vegetables", "nine colorful dish", etc. Even nowadays, Korean people are still habituated to increase the number of their dishes by the order of one, three, five, seven, nine and so on. All in all, the thesis is mean to prove that there is a deep relation between Korean people's dietetic culture and the doctrine of the five natural elements of the positive and negative. And we can prefer that the future of the development of Korean food will also be based on this theory. When people are paying more and more attention to dietetic cultures, it will be a royal way to know Korean people's cultural mentality through studying the doctrine of the five natural elements of the positive and negative.