In Japan, the decline of visual function, sleep problem and fatigue etc. of children is worried about with spread of Internet. Therefore the purpose of this study was to make clear the relationship between the Internet-addiction tendency and visual function, sleep situation and fatigue in junior high and high school students. The subjects were 625 students (379 boys and 246 girls) registered at a private junior high and high school in the metropolitan area. All research was conducted at the period from April to July 2015. The data of Internet-addiction tendency, naked vision, stereoscopic vision, bed time, wake-up time, sleeping hours, fatigue subjective symptoms were collected in this study. The eight items that were made based on the questionnaire of Young KS by Ministry of Health, Labour and Welfare study squad were used in the investigation of Internet-addiction tendency. The main results that was shown by the above survey were as follows; 1) The stereoscopic vision function of "morbid use" was significantly lower than "adaptive use" in high school students. 2) Similarly, there were the later bed time and the shorter sleep hours in “morbid use” than “adaptive use” in junior high and high school students. 3) Furthermore, the fatigue subjective symptoms of “morbid use” were higher than “adaptive use” in junior high and high school students.

  From these findings, we reached the conclusion that the visual function, sleep situation and fatigue subjective symptom of children were related to Internet use.