This study was performed in order to investigate the difference of general environment, life style, physical exercise, dietary behavior and food habit in primary school children in Incheon. We studied obesity incidence over 2 years among 1-6th grade primary school children. In 2009-2010, base line about 1,132 children was performed and in 2 years later, we reinvestigated health examination and questionnaire about several variables. this results were as follows: First, genenal characteristic was not significantly different, however BMI(body mass index) of total children were declined and BMI(body mass index) of obese children were significant difference. Second, It was a affirmatively exchanged health recognition and behavior of obesity with children, parents, teacher. Third, It was improved physical fitness and self-capacity of management in children. in conclusion, obesity incidence in primary school children was associated with physical characteristics, genetic factors and social factors like a life style. it is suggested that obesity management and appropriate regular exercise in family unit should be required to prevent obesity in children.