Purpose: The purpose of the study is to identify differences in BMI between early and late elderly people, and factors having influence of them. Methods: This study is an analysis of secondary data that used the raw materials from the KNHANES from 2008 to 2010. The subjects involved in the final analysis were 4,772 elders aged 65 or higher. Descriptive statistics, $x^2$-test and F-test, and CSGLM from the complex sample design were used for the data analysis with SPSS/WIN 19.0. Results: Significant differences were observed in the socio-demographic characteristics, health behaviors and diet habits between early and late elderly people. Adjusted for gender, location of residence, and living alone, the factors that affected BMI of the early elderly people included current smoking status, number of disease, difficulty in chewing, and number of meals per day while those that affected BMI of the late elderly people were current smoking status, number of disease, self-rated health, and difficulty in chewing. Conclusion: The study concludes that we should consider age-specific traits for monitoring the weight status of the elderly and providing appropriate weight management programs for the elderly.