The purpose of this study was to investigate the effect of group art therapy using Korean painting material on the self-expression of elderly patients with dementia. The subjects of this study were eight individuals in the experimental group and eight in the control among mild dementia over 65 years of age who were using J Home Care Center in K city and wanted to participate with the agreement of themselves and their guardians. Participants except two who were dropped out for health reasons of control group, were randomly deployed into the two groups and 60 minutes per session, a total of 16 sessions conducted for the period from July 2015 to October 2015. As research tools, the Art-Self and Communicational-Self Expression Ability Evaluation were employed for pre- and post-implementation and analysis. Data processing was performed by repeated measurement for comparative analysis and the characteristics of change in art and communication self-expression of the group members. And analyzed qualitatively, together with the characteristics of change when brushes and colored Korean papers were used. The results showed a positive effect on improving art and communication self-expression ability of elderly patients with mild dementia using Korean painting material into group art therapy. Therefore, it can be used in clinical field as a therapeutic approach to art therapy program for the elderly patients with mild dementia.