Aim:The aim of this study was to identify factors that influence changes in resilience among workers with mental health disorders, leading to effective treatment and support.Methods: Among the new patients at an institution, 81 who were working and had the ICD-10 diagnoses F3 and F4 were included. Resilience was measured at the initial visit and 3 months later using the S-H resilience test. Univariate and multiple regression analyses were conducted using the change in resilience between the two measurements as the objective variable, and treatment and attendance at work as explanatory variables.Results: There were no significant differences in resilience abilities between pre-and postmeasurement for the subjects as a whole. However, tests for the subgroups of diagnostic category, attendance at work, and treatment showed that resilience improved significantly in the mood disorder group, the leaving employment group, and the group receiving additional treatment. The results of the multiple regression analysis showed that treatment type (with or without additional treatment) had an effect on the degree of change in resilience, and among these "inpatient treatment" and "re-work program" were suggested to have an effect. Conclusion:The resilience of workers with mental health disorders was found to improve even after only 3 months of treatment, depending on the content of the treatment. We believe the significance of this study is the quantitative indication of the transition of resilience, which has not been made concrete until now.