Objective : The purpose of this study is to identify and understand the internal and external control of the caregivers of elderly with severe dementia and the effects of care stress on depression, and to provide basic data of occupational therapy intervention. Methods : The internal and external control, care stress, and depression were examined in questionnaires for the caregivers of elderly who were diagnosed with moderate or higher degree of dementia through CDR by medical institutions. Internal and external control and depression by care stress was analyzed by using independent samples t-test and ANOVA, and the effects of internal and external control and care stress on depression were analyzed by performing multiple regression analysis. Results : The results were as follow; The first, there was a significant degree of depression according to difference of internal and external control. The second, there was a significant degree of classification in the care stress. The third, the effects of internal controls and care stress on depression were shown to be statistically significant. Conclusion : Based on the analyzed results, the caregivers of elderly with severe dementia needs to seek the role of a occupational therapist who can enhance internal control and lower care stress in intervention of occupational therapy because internal control and care stress can affect depression.