Understanding child behavioral outcomes is important because early behavioral issues can lead to negative outcomes that persist throughout the life course. One characteristic that can affect child behavioral outcomes is parental psychological well-being. While there have been many studies describing the effects of parental psychological well-being on child behavior in the US, the nature of this relationship in non-Western countries has yet to be thoroughly explored. There is also limited research that distinguishes between the effects of both maternal and paternal psychological well-being on child behavioral outcomes. Japan is an interesting area in which to examine this relationship due to unique contextual factors that might affect parental psychological well-being, such as Japanese-specific patterns of maternal and paternal involvement. Utilizing regression analysis, this study examines the relationship between paternal and maternal psychological health and child internalizing and externalizing behavioral outcomes using two complementary longitudinal datasets from Japan (JCPS and JHPS). I find that maternal and not paternal psychological well-being is associated with child internalizing and externalizing behavioral problems. This may be a product of fathers in Japan being less engaged in parenting or the intense relationship mothers are encouraged to develop with their children. Further research on this relationship can help in investigating the universality of Western findings related to paternal and maternal psychological health and child behavior.