Objectives: The purpose of this study was to examine the moderated mediating effect of negative emotionality through inhibitory control on the relationship between maternal parenting and aggression. Methods: Participants were 277 toddlers, who were 24 to 35 months, and their mothers and homeroom teachers. A scale of toddlers aggression: TBC (12 questions), a scale of inhibitory control: BRIEF-P (16 questions), a scale of negative emotionality: ECBQ-short (12 questions) and a scale of mother's parenting sensitivity (9 questions) were used. Data were analyzed for the moderated mediating effect between variables using PROCESS macro methods. Results: The main findings were as follows. First, inhibitory control mediated the relationship between mothers' parenting sensitivity and aggression of toddlers. Second, negative emotionality significantly moderated the relationship between mothers' parenting sensitivity and inhibitory control. Last, the mediating effect of inhibitory control was moderated by negative emotionality in the relation between mothers' parenting sensitivity and aggression of toddlers. Conclusion: These results support Belsky's differential susceptibility model. When the level of negative emotionality is average or above, the more sensitive and responsive the increase in maternal parenting behavior through inhibition control, which has been confirmed to reduce aggression. Implications of the intervention of early intervention program and parent education are also discussed.