Purse: The purpose of this study was to examine the effect of a laughter therapy on mental health promoting like depression, laughing index of elderly. Methods: The study was conducted based on the non-equivalent control group pretest-posttest design. The participations included 12 older adults in the control group and 11 in the experiment group. Data was collected from October 1 to November 22, 2013. Experimental group participated in laughter therapy six times, once a week for 60 minutes of each session. Questionnaires were used to measure pretest and posttest levels of depression and laughing index. Results: At the end of six-week intervention, depression score (z=-2.95 p=.003) and laughter index score (z=-2.81 p=.005) was significantly decreased in the experimental group compared to the control group. Futhermore, there was a significant difference in the depression scores of the experiment group at the posttest, but no signigicant difference was found between the two groups. Conclusion: The study results suggest that the laughter therapy is an effective intervention to reduce the depression but helpful to enhance the laughing index. Therefore, it is expected that laughter therapy will serve as an emotional nursing intervention for elderly patients with depression.