ObjectivesThe association between poor parenting and dental caries in children remains unclear. We investigated the association of poor parenting with dental caries and oral health behaviour among children aged 6‐7 years in Japan.MethodsTwo waves of repeated cross‐sectional surveys on children and their caregivers in Adachi City, Tokyo, were analysed. Questionnaires on parenting behaviour and the child's oral health behaviour were distributed through schools and completed by 8499 caregivers (response rate = 80.8%). The number of decayed or filled primary teeth (dft) at school dental health check‐ups was linked to the survey data (N for complete case analysis = 6309). Factor analysis was performed to identify types of poor parenting: poor involvement, child abuse and lack of supervision of a child's health behaviours. The association between factor scores (z‐score), the number of dft and oral health behaviour (not brushing teeth twice a day, not controlling snack eating habits and drinking juice every day) was evaluated by Poisson's regressions adjusted for covariates, including caregiver's socioeconomic status.ResultsPoor involvement and lack of supervision of a child's health behaviours were positively associated with dft (mean ratio, MR [95% confidence interval, CI] =1.05 [1.03, 1.07] and 1.18 [1.16, 1.21], respectively) and unhealthy oral health behaviours. Child abuse was not associated with dft (MR = 0.99 [0.96, 1.01]) but was associated with all three unhealthy oral health behaviours (prevalence ratio, PR [95% CI] were 1.11 [1.06, 1.16], 1.11 [1.06, 1.16] and 1.06 [1.00, 1.11] for not brushing teeth, not controlling snack eating and drinking juice, respectively).ConclusionsPoor involvement and lack of supervision of a child's health behaviours were associated with dental caries, and any type of poor parenting was associated with poor oral health behaviour among children.