This study investegated the positive effect of the urban agriculture experience program on the mental health of the elderly by measuring the mental health indices of stress and depression. The research subjects included an experiment group of seniors over 65 years old who participated in the program for over six months and a control group of seniors, whom resided in the same city. Stress and depression were surveyed as mental health indices, and the physiological disparity was measured to clarify the disparity in the autonomic nervous system. The collected data were analyzed with t-test using the SPSS WIN 12.0. The results of the stress index analysis revealed that, in terms of communication, stress scores related to loneliness were statistically significantly lower for the experiment group than the control group. Also, in terms of health, the stress levels of the experiment group tended to be significantly lower than the control group. The depression index analysis showed the control group had a much higher level of depression than the experiment group with considerably significant disparity. The autonomic nervous system analysis revealed the stress index was significantly lower for the experiment group than the control group, and also, in terms of pulse diversity, the experiment group was within the range of normality, whereas the control group was exposed to the influence of chronic stress. The research results showed that urban agriculture activities applied to the elderly stabilizes the sympathetic nerve and activates the parasympathetic nerve to increase the resistance against stress.