The purpose of this study was to examine the effects of group art therapy on parenting stress and state anxiety of mothers with preschool children. The data was collected from the beginning of September to November, 2016 at two different preschools in ‘E’ district, Seoul. The participants were the mothers of preschool children. 18 participants were selected, and they were divided into two groups: 9 were assigned in the experimental group, and 9 were assigned in the control group. The group art therapy sessions were provided to the experimental group for 60 minutes, 2 to 3 times a week, 12 sessions in total. For the pretest and posttest, Parenting Stress Index/ Short Form(PSI/SF), State-Trait Anxiety Inventory(STAI-Y1) and Draw-A-Person-in-the-Rain(DAPR) were conducted to the experimental group. The results showed that first, after the group art therapy was provided, there was statistically significant decrease on parenting stress of the experimental group. Second, there was statistically significant decrease on state-anxiety of the experimental group. The results of qualitative analysis on DAPR showed that there were positive differences of participants’ perception on stressful situation. It also showed that participants made good use of stress coping resources, and their ability to cope with stress has improved. The results of this study shows that the group art therapy had positive effects on decreasing parenting stress and state anxiety of mothers with preschool children. This study proved that mothers with general preschool children also have parenting stress and state anxiety, and the group art therapy had positive effects on them. The significance of this study lies in the fact that it suggests the necessity of supporting psychological stability of mothers with general preschool children.