Objectives: Based on the results that the use of a mobile app program based cognitive behavioral therapy, the Todac Todac, was effective in improving depression in individuals with general depressive disorder, this study was intended to determine whether the use of this app would be effective in improving depression in dialysis patients. Methods: Sixty-five end-stage kidney disease patients receiving dialysis at Soonchunhyang University Cheonan Hospital were randomly assigned to the Todac Todac app program (experimental group) or a daily mood chart app program, E-moods (control group) for three weeks. The degree of depression was measured by the state anxiety index and trait anxiety index, Beck depression index, and dysfunctional attitude scale (DAS)-K index before and after using the app. Results: After the end of the 3-week program, there were no differences in the anxiety index, Beck depression index, and DAS-K index between the experimental group and the control group, and there was no difference according to dialysis method or age. In the subgroup analysis, only non-diabetic patients under 50 showed improvement in some depression indicators. Conclusions: The Todak Todak, a mobile app program-based cognitive behavioral therapy, seems to have a limited effect on improving depression in dialysis patients. Therefore, it is necessary to develop new tools to improve depression in dialysis patients