Background Untreated caries is the most prevalent disease in the world. A sense of coherence (SOC) is believed to contribute to oral health. However, it is unclear whether the contribution of SOC is larger among children with lower socioeconomic status (SES). We aimed to clarify the association between guardians' SOC and their children's caries based on socioeconomic status (SES) in Japan.Methods This study's subjects were Japanese public junior high schoolers, aged 12-15, and their guardians. We administered a questionnaire survey among guardians in 2016 to assess their SOC and family environment. With their students' consent, public junior high schools shared the results of the dental examinations that were part of their school physicals. Multivariate logistic regression was conducted to clarify the association between guardians' SOC and their children's untreated decayed permanent teeth. We also conducted a stratified analysis according to a relative poverty line. Furthermore, the interaction between annual equivalent incomes, educational attainment with guardians' SOC was evaluated by including the interaction term respectably.Results Proportion of untreated decayed permanent teeth of adolescents was 9.37% for 12 -13 years, 9.02% for 14 years, and 11.78% for 15 years. Guardians' SOC score was 15.1 (SD 3.2, range 3 -21).We observed in the multivariate regression, a significant inverse association between children's untreated decay and their guardians' SOC (OR 0.93, 95%CI 0.87-1.00). Equivalent annual income had a significant marginal association with decayed teeth (OR 0.14, 95%CI 0.02-1.04). The association of SOC was stronger in the low economic group (OR 0.64, 95%CI 0.43-0.95). The interaction terms of educational attainment and guardians' SOC was not significant. In the high economic group, educational attainment was significantly associated with decayed teeth (OR 0.50, 95%CI 0.27-0.91).The interaction terms of educational attainment and guardians' SOC was not significant.Conclusions Guardians with higher SOC were associated with children having fewer caries. Guardians' SOC is an important factor for the incidence of caries and access to dental care, especially among children with low economic status.