The purpose of the study was to investigate the level of health behavior of school-age children and to identify the predicting variables of the school-age children's health behavior. The subject were 467 children in grades four to six, enrolled in two elementary schools located in two cities. The mean age of the subject was 10.03(SD=1.33). The data were analyzed using t-test, ANOVA, correlation analysis, and stepwise multiple regression. The result are as follows: 1. The mean of the score of health behavior of the school-age children was 154.6, showing thar they are practicing health behavior relatively well. 2. There were significant differences in the mean scores of health behavior according to grade(F=6.53, p=.001), sex(t=-3.70, p=.000), educational level of the parents(F=4.92, p=.002; F=4.47, p=.004), occupation of the patients(F=3.31, p=.003;F=4.76, p=.000), and socioeconomic status(F=11.87, p=.000). 3. There were significant correlations between health behavior and health motivation(r=.53, p=.000). self-concept(r=.32, p=.000), perceived health status(r=.16, p=.000), and health locus of control(r=.15, p=.001). 4. Health motivation, self-concept, grade, socioeconomic status, and health locus of control were identified as predictor variables of health behavior of the school-age children from the stepwise multiple regression analysis. The total percent of variance accounted for by these five variables was 35.0%. From the result, it is suggested that in the development of a school health education program, the effect of health motivation and self-concept to promote student's health behavior in school-age children should be considered.