The purpose of this study was to assess how art therapy changes the depression and anxiety of children who experienced mother-to-son separation and what experiences art therapy brings to the father-to-son relationship. The study targets a 9-year-old boy who was a sophomore in elementary school in B area, and although the child was saddened by bereavement, his mourning process seemed delayed due to difficulties in expressing their feelings, showing off their feelings, and continuing to show off or exaggerate his relationships with others. Accordingly, once a week art therapy sessions, biweekly child counseling sessions, in the final stage, four sessions total of father-son cooperative sessions were held; and a total of 27 art treatments and 12 rounds of counseling were conducted excluding pre-, after-test, and post examination. The results showed that significant changes in the scale of depression and anxiety appeared in the Korean verion of the child Behavior Checklist (K-CBCL), and the Home-Tree-People Figure Test (HTP), Dynamic Familyization (KFD), and sentence completion test (SCT) were found to result in adaptations to changes in the home environment and daily life. Thus, as a result of experiences in individual art therapy stages and sub-consultations, children could express the mourning process for mock bereavement in a safe way and experienced positive changes in depression and anxiety reduction.