Although pubertal timing is gradually becoming earlier in Japan, support as for physical and mental health among children experiencing earlier puberty than their peers is inadequate. To better understand health and life satisfaction in seventh grade students (age 12-13 years), examination of relationships between health outcomes and pubertal timing, socioeconomic status, and lifestyle factors is necessary.Participants of the Toyama Birth Cohort Study (4,752 males and 4,740 females) answered questions regarding school year of onset of voice break for boys and menarche for girls, sleep quality, mental health difficulties, overall health, quality of life (QOL), and lifestyle. Relationship between health outcomes and pubertal timing was examined using binary logistic regression analysis.Earlier pubertal timing was associated with four health-related outcomes. For poor sleep quality, the adjusted odds ratio (OR) of fourth grade males and crude OR of fifth grade females were statistically significant. Regarding mental health difficulties, the crude OR of fifth grade males and adjusted OR of fourth, fifth, and sixth grade females were statistically significant. Associations between poor overall health and fourth grade males and fourth or fifth grade females were observed. For poor QOL, the adjusted OR of fourth grade males and females was statistically significant.Relationships between earlier pubertal timing and poor sleep quality, mental health difficulties, poor physical health, and poor QOL were observed. To improve children's quality of life, support from teachers and school doctors and nurses is needed-especially for children with earlier pubertal timing.