The purpose of this study is to investigate the factors affecting family caregiver financial burden of out-of pocket expenses for the nursing home service under Long-term Care Insurance System. We conducted a national cross-sectional descriptive survey from July to September 2010 to collect data based on the long-term care benefits cost specification. Total 1,016 family caregivers completed questionnaires. 185 subjects of total were excluded from the data analysis due to being answered by user(18 cases), or caregivers not to pay for services expenditures(122 cases), having a missing data on family caregivers characteristics(45 cases). Finally, 831 subjects were included in the study. The average financial burden was 3.18(${pm}0.71$). We divided subjects into two groups by level of burden, high-burden group and low-burden group. In the result of the multiple logistic regression analysis, family caregiver financial burden was significantly higher in family caregivers with ages 40 to 49 compared to less than 40, lower educational level, unsatisfaction for long-term care service, high percentage(more than 50%) of cost-sharing and high total out-of pocket expenses(more than 300,000 won) for long-term care services. Also, Family caregivers who are spouse felt higher financial burden compared to son. This study is meaningful as the first attempt to measure family caregiver financial burden for long-term care service and to identify factors affecting the financial burden. Family caregivers felt financial burden of out-of pocket expenses for the nursing home service. The policy makers, the insurer, and the providers need to pay attention to ease family caregiver financial burden.