<p>Purpose: To clarify environmental conditions and the lifestyle determining the QOL of upper-grade elementary school children by analyzing the QOL levels among a group of children.</p><p>Method: We conducted a survey of 433 upper-grade children in September 2007, who belonged to three public elementary schools in one region in Yamanashi Prefecture, using the Japanese Kid-KINDL Questionnaire, consisting of six domains: physical health, emotional well-being, self-esteem, family, friends, and school. We also investigated their lifestyle, associated with: eating breakfast every day, bedtime, playing outside after school, lessons, time spent with video games, the amount of TV and computer use.</p><p>Results: 409 questionnaires were analyzed as follows:</p><p>(1) The QOL, emotional well-being and family scores of 4th graders and 5th graders were higher than the equivalent findings of Shibata (standard population). In addition, the physical health and school scores of 4th graders were higher than those of the standard population. Conversely, the physical health scores of the 5th graders were lower than those of the standard population. No special QOL characteristics were observed for sixth graders.</p><p>(2) The family and school scores of females were higher than those of males.</p><p>(3) Each QOL score and the 5 domains scores except for friends tended to decrease as the grade level increased, especially regarding self-esteem and school.</p><p>(4) Children who resided in the most densely-populated areas within the region had higher QOL scores and the 5 domains scores except for family. Conversely, children who resided in suburbs with many agricultural households within the region had higher family scores.</p><p>(5) Lower QOL and school scores were significantly associated with “sleeping after 2:00" (odds ratio; [95% confidence interval] after adjusting for sex and grade) (1.74 [1.05, 2.87], 1.97 [1.16, 3.37]) ; A lower physical health score was significantly associated with “skipping breakfast" (3.59; [1.06, 12.16]) ; A lower self-esteem score was significantly associated with “sleeping after 2:00" and “using games, television and computers more than 3 hours" (2.20; [1.30, 3.71], 2.53 [1.45, 4.43]) ; A lower family score was significantly associated with “using video games, television and computers more than 3 hours" (2.52 [1.49, 4.27]) ; and a lower friend score was significantly associated with “not playing outside" (4.63 [2.14, 10.0]). No relationship with emotional well-being was observed.</p><p>Conclusion: Our QOL results for Elementary School Children indicate that strong relationships were observed among such factors including “sex" and “grade", environmental conditions including the “industrial structure" and “population size", and lifestyle including “eating breakfast" and “bedtime", etc..</p>