This study aimed to verify the effect of group art therapy using grids to improve the visuospatial ability of mild dementia. The study subjects were elderly people with mild dementia who received care from T or S day care center and agreed to participate. They were divided into 2 groups, the control and the experimental, 16 subjects each. A group art therapy was conducted twice a week for 60 minutes each session, a total of 14 sessions from September 27 to November 17, 2022. To verify the quantitative effects, RCFT was conducted before and after the art therapy program and its change was measured. For quantitative analysis results, statistical differences were measured through a paired sample T-Test. As a result, the score of visuo-constructional ability, as the sub-area of visuospatial function, was increased in the experimental group, post-test, 27.42(SD=6.966) compared to the pre-test 22.33(SD=6.313). The scores of immediate recall from 5.15(SD=4.753) to 9.32(SD=8.287), and the score of recognition from 15.19(SD=2.738) to 18.75(SD=2.436). There was a significant difference between pre- and post-test scores in the experiment group but not in the control. In addition, as a result of the analysis of changes, it was confirmed that positive changes in visuospatial ability were confirmed, and linguistic nonverbal expressions increased psychological satisfaction. Based on these findings, the significance and limitations of this study were discussed.