We administered a self‒reporting questionnaire survey regarding the mental health conditions of high school students and attitudes of students and their teachers toward students’mental health issues. In addition, we discussed the requirements for high school students’ mental health support system. The subjects were 3,312 students and 208 teachers in four Shizuoka prefectural public high schools in 2009. University Personality Inventory（UPI）is usually conducted to assess university students’ mental state and is a questionnaire that high school students can answer easily. Therefore, we adopted UPI for this survey. UPI was composed of 56 unhealthy and 4 healthy condition items. High school students completed the UPI and determined the sum of unhealthy condition items；a higher score indicated a poorer mental health status. The average UPI score of all students（n＝3,312）was 12.7 points, and that of females（n＝1,217）was 15.2 points, which was significantly higher than the 11.3 points of males（n＝2,095）. Those with scores ≥30 points（7.5％）, which was more than half of the maximum score, were designated as the High Score（HS）group and considered to have poor mental health. Those with scores of ≥40（1.4％）seemed to have very poor mental health, and there was concern that they may be suffering from psychosis. Our observations indicated that HS students were likely to avoid seeking help regarding mental health issues, which was especially true for male HS students. The majority of students chose their friends and parents as advisers, but HS students were significantly more likely to choose advisers who were engaged in jobs related to medical work. Students in both the HS and non‒HS groups who did not wish to consult anyone else about their mental conditions wanted to be approached by those around them. High school teachers hesitated to intervene with mentally disturbed students and attempted to resolve problems within the school. Thus, it appears necessary for families, school teachers, and psychiatrists to build closer relations with each other to promote mental health among high school students.