This study compared the mental health of adolescents in three countries in northeast Asia: Japan, South Korea, and China. The study sample included a total of 1,399 third graders at junior high schools: 632 from Yonago City and Tottori City in Japan, 377 from Wonju City in Korea, and 390 from Changchun City in China. Mental health was measured by the Ochanomizu University Health Examination, which includes mental health scales composed of somatic symptoms, eating disorders, depression, interpersonal relationships, powerlessness, and impulsiveness; self-resilience; familial relationships; friendships; a feeling of gloom during the previous month; current well-being; and counseling. The results of this study were as follows: first, Japanese students experienced more difficulties in interpersonal relationships and experienced more feelings of powerlessness than Korean and Chinese students. Korean students were vulnerable to somatic symptoms and impulsiveness, whereas Chinese students experienced more depression than Korean and Japanese students. Second, more female students were in the poor mental health group than male students. Third, Japanese female students ranked the lowest of all groups for the Resilience Index scores. Fourth, when in need of counseling, students solicited advice from teachers (classroom teachers, health teachers or club teachers) about their study-related problems, and asked for advice from friends regarding problems or worries about peer and family relations. However, a number of students received no counseling for their troubles. The study concluded that it is necessary to promote a healthy environment for students, with easy access to counseling from mental health care professionals.