This study aimed to analyze the effects of a horticultural occupation therapy program using a healing garden on the emotional rehabilitation of patients with acute and chronic mental disorders, and to identify the possibility of using horticultural occupational therapy as a mental rehabilitation service to promote the social rehabilitation of patients with mental disorders. In this study, 20 patients diagnosed as chronic mental disorder at Seoul Metropolitan E hospital and 22 as acute mental disorder at Incheon H hospital were divided into 2 groups for Horticultural occupation therapy (HOT) and Group occupational therapy (GOT). General occupational therapy was provided 4 times a week for the experimental groups of patients with chronic and acute mental disorders, and a horticultural occupational therapy program using a healing garden was provided only once a week, a total of 12 sessions, for the experimental groups. For the control groups of patients with acute and chronic mental disorders, occupational therapy was provided 5 times a week only. Among the acute mental disorder patients, the treatment group showed a significant decrease in Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI) and emotional stress scale (ES), whereas the control group didn’t (p<.001). On the other hand, such significant changes were not seen among the chronic GOT. Futhermore, the chronic HOT showed the significant effect in physical stress scale (PSE).