The purpose of this study was to investigate elementary school children's internet use and addiction and to analyze the differences in their self-esteem, loneliness, and peer relationship by the type of internet use and the level of internet addiction. Four hundred and sixty-eight children who were fifth or sixth graders participated in this study. The subject were classified in three sub-types of internet use(simultaneous social type, non-simultaneous social type, and non-social type) and three sub-levels of internet addiction(normal group, addiction oriented group, and addicted group). The results showed that 37.9% of the subject was normal, 50.1% was addiction oriented, and 11.9% was addicted. Second, simultaneous social type was the most frequent type. Third, the percentage of addiction oriented and addiction groups in the simultaneous social type was comparatively large. Lastly, the main effect of the level of internet addiction on children's self-esteem was found. Also, the main effect of all independent variables and interactional effects between the type of internet use and the level of internet addiction on children's loneliness and peer relationship were determined as a result of this study. These results indicate that elementary school children's internet addiction and psycho-social characteristics should be differentially understood as the type of internet use