The purpose of this study is to seek solutions for the adverse effects of the informatization by analyzing the influential factors of internet addiction to maximize prevention of the internet addiction for highschool students. The causal factors of the internet addiction are classified into three categories: personal factors, familial factors, and social environmental factors. To validate the study, the questionnaires were given to four high schools which were two generalized high schools and two specialized high schools in the Seoul and Kyunggi Area. The most influential factor of the internet addiction was identified, and hierarchical influence among factors were analyzed by evaluating the questionnaires. The result of the generalized high schools was different from that of the specialized high schools. It proved that different countermeasures must be prepared depending on environment of internet users. Therefore, diverse and comprehensive solutions for internet addiction must be devised to solve the problem of internet addiction.