This study aimed to identify the effect of reminiscence-oriented group art therapy using seasonal customs on the memory and depression of the elderly with mild dementia. It was conducted for seven community-dwelling seniors who had been diagnosed with the mild dementia, from December, 2014 to April, 2015, for 24 sessions twice a week for 90 hours each. To verify the program's effects, degrees of cognition, memory and depression were compared in terms of pre-post scores. Also changes in behavior and linguistic usage in each session were examined while searching for differences on LMT and artistic, linguistic expressing ability. The Wilcoxon signed rank test was used for analyzing the change of pre-post program. The results revealed that reminiscence- oriented group art therapy using seasonal customs had a positive effect on an increase of the memory and a decrease in depression for the elderly with mild dementia. Because the elderly with dementia have difficulty with free reminiscence and expression and have few opportunities for mutual communication in interpersonal relations, this study has significance in that it reorganized individuals to joint works and induced group dynamics through physical and sympathetic activities. Particularly, it was effective in the improvement of the memory and the decrease of depression of the subjects by expanding art work centered on plane to dimensional work.