The aim of this study was to investigate the effect of the individual cognitive-behavioral treatment for anxious children on maternal parenting stress and to examine the relationships of anxious and behavioral symptoms of children with parenting stress of their mothers. Participants who were 16 children aged 8 to 12 years (mean = 9.25, SD = 1.26) with anxious symptoms and their mothers were recruited into the individual cognitive-behavioral treatment for sixteen weeks. The Taiwanese version of the Multidimensional Anxiety Scale for Children (MASC-T) and the Child Behavior Checklist (CBCL) were applied to evaluate the anxious and behavioral symptoms of children, respectively. The Parenting Stress Index (PSI) was applied to evaluate parenting stress of their mothers. These assessments were given on 1st, 9th and 16th weeks and analyzed using Generalized Estimating Equation (GEE). The results indicated that the scores on the total PSI and child domain improved with the treatment, but not on the PSI parent domain. GEE also showed that children’s severities of anxious and behavioral symptoms were positively associated with the severity of mothers’ parenting stress. The results support the hypothesis that the severity of parenting stress related to having a difficult child improved with the treatment. However, parenting stress related to parent’s functioning, the competence the parents feel, and aspects of life didn’t improve with treatment.