This study examines the mediating effect of fathers’ parenting stress on the relationship between paternal marital conflict and internalizing and externalizing problem behaviors in 7-year-old children. Participants included 1,414 households from the Panel Study on Korean Children (PSKC, 2015) conducted by the Korea Institute of Child Care and Education, all of whom provided complete responses to key variables. A cross-sectional design using secondary data was employed. Paternal marital conflict and parenting stress were reported by fathers, while children’s problem behaviors were assessed using the mother-reported Child Behavior Checklist(CBCL) 6-18. Data were analyzed using SPSS 31.0, including Cronbach’s alpha, descriptive statistics, frequency analysis, Pearson correlation analysis, and PROCESS Macro Model 4. Child gender, parental education level, employment status, and monthly household income were controlled. Results indicated that fathers’ parenting stress partially mediated the relationship between paternal marital conflict and children’s internalizing and externalizing problem behaviors. These findings suggest that marital conflict affects children’s behavioral problems both directly and indirectly through fathers’ parenting stress. The study highlights the need for tailored parent education, psychological support programs, and interventions to improve marital relationships.