This study aims to conduct art therapy to alleviate anxiety and language expression problems in a child residing in a foster facility and examine the changes resulting from the therapy. The study participant was a third-grade elementary school boy. Art therapy sessions were conducted once a week, with each session lasting 50 minutes, totaling 27 sessions. After each session, We had a 10-minute counseling session with the child's caregiver or counselor from the foster care facility. The study utilized the House-Tree-Person (HTP) drawing test to examine changes in the drawings before and after the therapy. The changes in anxiety and language expression problems were also presented based on the child's verbal and non-verbal expressions during the art therapy sessions and their artwork and reports from caregivers and counselors from the foster care facility. The results of this study are as follows. Firstly, the anxious behaviors of the children decreased after art therapy. Secondly, the children's language expression increased and became clearer after art therapy. Thirdly, changes were observed in the children's HTP drawings after art therapy. In other words, compared to the pre-assessment drawings, the post-assessment revealed positive changes such as shifts in the positioning of elements, the smoke from chimneys, the presence of branches and leaves on trees, natural movements in figures, and appropriate body proportions. These changes indicate a decrease in the child's anxiety and increased flexibility. Therefore, we concluded that art therapy effectively reduced anxiety and improved language expression in the child residing in foster care facility.