Purpose: This study was conducted to describe parenting stress in mothers of preschoolers who were born prematurely and to determine factors affecting parenting stress in child’s problem behavior, mother-child interaction and parenting alliance. Methods: An exploratory survey study was conducted with 66 mothers of preschool children (5~6 years) with preterm births (PTB). Data were collected using Parenting Stress Index (PSI), Child Behavior Checklist (CBCL), Mother-Preschool Child Interaction Scale (MPIS), and Parenting Alliance Inventory (PAI). Results: Of the 66 mothers, 8(12.1%) showed high scores that were more than borderline for the PSI total score. In the multiple linear regression analysis, lower scores on the PAI (β=-.41, p<.001), higher scores on the externalizing problem behavior of the CBCL (β=.40, p=.001), and lower scores on the MPIS (β=-.21, p=.043) were statistically significant contributors to maternal parenting stress. Conclusion: Findings indicate that mothers of PTB preschool children are at risk for parenting stress. Child’s externalizing problem behavior, poor maternal- child interaction and parenting alliance were independent factors raising maternal parenting stress. More attention is needed on paternal parenting support, child’s behavioral development, interaction with children for effective prevention and management of maternal parenting stress of PTB young children.