This exploratory study sought to compare the parenting variables of parenting stress, perceived social support, and parenting styles among Japanese mothers (n = 42) of children with autism and those (n = 36) without autism, and examine associations between children's internalizing and externalizing behaviors and these variables by using parent questionnaires. Results of independent t-tests revealed increased parenting stress symptoms among mothers of children with autism and lower levels of social support. Parenting styles did not significantly differ between the groups. Regression analyses revealed that parenting stress predicted externalizing behaviors in children with autism. Additionally, an authoritarian parenting style was predictive of externalizing behaviors in children without autism. Parenting stress was also related to authoritarian and permissive parenting in both groups. These findings highlight the need for interventions and mental health services that reduce parenting stress and improve maternal well-being, and therefore, enhance parent-child interactions.