Objective: Parents of children with attention deficit hyperactivity disorder (ADHD) experience elevated levels of stress in their parenting role. Understanding what contributes to such stress is important for its management. Methods: We assessed associations between child and parent characteristics and parenting stress in Japanese mothers of 6-12-year-old children with ADHD recruited through the community (n = 51) and hospital child psychiatry/pediatric clinics (n = 124). Hierarchical multiple regression analyses assessed the extent to which child symptom severity (ADHD and ODD), parenting efficacy, depression, and maternal ADHD symptoms explained variance in both child-domain and parent-domain parenting stress. Results: Child symptom severity and maternal depression accounted for significant variance in child-domain parenting stress. Child ODD, parenting efficacy, depression, and maternal ADHD (clinic sample) explained significant variance in parent-domain parenting stress. Exploratory cross-sectional mediational analyses highlight the inter-relatedness of the associations between parenting-efficacy, maternal depression and parent-domain parenting stress. The association between maternal ADHD and parent-domain parenting stress is statistically fully mediated by maternal depression. Conclusion: The pattern of associations between child and parent characteristics and parenting stress in Japanese mothers of children with ADHD are consistent with Abidin's model of parenting stress with implications for clinical management.