BackgroundPathological gaming (PG) has emerged as one of the major public health concerns worldwide. We aimed to assess PG and its associated factors among elementary school children in Japan.MethodsWe conducted a school-based observational study in Toyama, Japan in 2018. In total, 13,413 children in the 4th–6th grades (mean age, 10.5 years) participated in the study. We distributed questionnaires and inquired about their lifestyle, irritability, and school and family environments. Referring to criteria of gaming disorder in the International Statistical Classification of Disease (ICD-11), we asked about three core symptoms: impaired control over gaming, increasing priority given to gaming over other activities, and continuation of gaming despite the negative consequences. Children who had all three criteria in the questionnaire were defined as PG.ResultsThe response rate was 97.6%, and 11,826 children were included in our analyses (88.2%). The prevalence of PG was 5.6% (7.8% in boys, 3.2% in girls). Besides sex, PG was significantly associated with lifestyles, including skipping breakfast (odds ratio [OR] 1.33; 95% confidence interval [CI], 1.05–1.68), physical inactivity (OR 2.23; 95% CI, 1.63–3.05 for rare), late bed time (OR 2.52; 95% CI, 1.96–3.25 for ≥11 p.m.), frequent irritability (OR 1.89; 95% CI, 1.47–2.43), frequent feeling of school avoidance (OR 1.92; 95% CI, 1.49–2.46), fewer close friends (OR 1.30; 95% CI, 1.08–1.56 for some), low academic performance (OR 1.53; 95% CI, 1.13–2.08), no child–parent interaction (OR 1.34; 95% CI, 1.02–1.75), and no rules at home (OR 1.21; 95% CI, 1.02–1.43).ConclusionUnhealthy lifestyles, irritability, and low functioning in school and family environments were associated with PG. Besides having a healthy lifestyle, parental involvement appears to be an indispensable countermeasure for PG in children.