This study was conducted to examine obese children's self-efficiency feeling and health promotion behavior in order to provide basic information on prevention of children obesity. Data were collected in June, 2001 from 349 normal weight children and 351 obese children, who were fifth or sixth graders at 14 primary schools located in Seoul, Busan, Daegu, Gwangju, Ansan, chungju, and Gumi. The data were analyzed through using Chronbach's $\alpha$, frequency analysis, $X^2-test$, ANOVA, and Pearson correlation. The results of this study can be summarized as follow. 1. The factor of children obesity was significantly different in the variables of sex, parents obesity, brother or sister obesity, father's occupation, level of living, health condition, and satisfaction level with their bodies. On the other hand, it was not significantly different in the variables of father's education level, mother's education level, mother's occupation, level of father's concern about health, and level of the children's concern about health. 2. In the case of normal weight children, dietary efficiency feeling was significantly different in the variables of level of father's concern about health and level of children's concern about health. In th case of obese children, the dietary efficiency feeling was significantly different in the variables of mother obesity, parents' education level, father's occupation, and the children's satisfaction level with their bodies. In the case of normal weight children, exercise efficiency feeling was significantly different in the variables of sex, level of parents's concern about health, and level of the children's concern about health. In the case of obese children, the exercise efficiency feeling was significantly different in the variables of grade, brother and sister obesity, parents' education level, father's occupation, and the children's satisfaction level with their bodies. In the case of normal weight children, social efficiency feeling was significantly different in the variables of brother and sister obesity, parents' education level, level of parents' concern about health, and level of the children's concern about health. In the case of obese children, the social efficiency feeling was significantly different in the variables of parents' education level, father's occupation, level of living, the children's health condition, and the children's satisfaction level with their bodies. 3. In the case of normal weight children, personal hygiene was significantly different in the variables of sex, level of parents's concern about health, and level of the children's concern about health. In the case of obese children, the personal hygiene was significantly different in the variables of parents' education level, father's occupation, mother's occupation, level of living, and level of parents' concern about health. In the case of normal weight children, dietary habit was significantly different in the variables of sex, level of parents's concern about health, and level of the children's concern about health. In the case of obese children, the dietary habit was significantly different in the variables of father's education level, mother's education level, level of living, and the children's satisfaction level with their bodies. In the case of normal weight children, exercise habit was significantly different in the variables of grade, sex, father's education level, mother's education level, and level of children's concern about health. In the case of obese children, the exercise habit was significantly different in the variables of grade, mother obesity, parents' education level, father's occupation, level of parent' concern about health, the children's health condition, and the children's satisfaction level with their bodies. In the case of normal weight children, prevention of infectious diseases was significantly different in the variables of sex, father's occupation, level of parents' concern about health, and level of the children's concern about health. In the case of obese children, the prevention of infectious diseases was significantly different in the variables of mother's education level and father's occupation. In the case of normal weight children, prevention of accident was significantly different in the variables of mother's education level, level of parents' concern about health, and level of the children's concern about health. In the case of obese children, the prevention of accident was significantly different in the variables of brother and sister obesity and mother's occupation. In the case of normal weight children, mental health was significantly different in the variables of father obesity, brother and sister obesity, parents' education level, and level of the children's concern about health. In the case of obese children, the mental health was significantly different in the variables of parents' educational level, father's occupation, mother's occupation, level of living, and the children's health condition. 4. According to the correlation between self-efficiency feeling and health promotion behavior, the higher the self-efficiency feeling was, the higher the level of health promotion behavior was. 5. The children obesity was influenced by the factors of level of living, level of parents' concern about health, the children's health condition, level of the children's concern about health, the children's satisfaction level with their bodies, dietary efficiency feeling, exercise efficiency feeling, social efficiency feeling, personal hygiene, dietary habit, exercise habit, prevention of infectious diseases, prevention of accident, and mental health. From the results of this study, it is clear that obese children's self-efficiency feeling is closely related with health promotion behavior. Therefore, it is necessary to strengthen children's self-efficiency feeling in order to make children control efficiently obesity for themselves.