Purpose: In Korea, the prevalence of dementia patients has increased, which makes the care burden of nurses important. The purpose of this study is to identify factors affecting the care burden of nurses caring elderly patients with dementia. Methods: A cross-sectional design was conducted using a convenience sample of 127 nurses from two hospitals and a nursing home in Korea. Participants completed questionnaires on knowledge of and attitudes toward dementia, social support, self-esteem, dementia problematic behavior (DPB), and professional caregiver burden index. The data were analyzed by using the t-test, ANOVA, Pearson correlation, and multiple regression with the SPSS/windows version 21.0 program. Results: The influencing factors for nurse burden include day shift, DPB, self-esteem, social support, which explain 28.0% of care burden of nurses. Conclusion: To reduce the burden of the nurses, there needs to be an administrative system that focuses on enhancing their self-esteem and social support. Active institutional support may be necessary for the nurses taking care of elderly patients with dementia.