The purpose of this study was to grasp relationship between obesity and dental caries. A research was performed by utilizing raw data of the 3rd year(2009) in the 4th term for Korean National Health and Nutrition Examination Survey, which is a survey of health and nutrition in the national unit for the Republic of Korea. The research subjects are finally 7,393 people except the subjects with missing of variables relevant to obesity and dental caries among adults aged over fully 19 years old. Data analysis was used SPSS 18.0 program. As a result of analyzing with significant level in 0.05, the following conclusions were obtained. 1. Overweight(${eta}$ = -0.12, p = .02) was indicated to be low in number of DT pieces compared to normality. 2. Obesity(OR = 0.69, 95% CI: 0.57, 0.84) was indicated to be low in possibility of having DMFT compared to normality. 3. Overweight(${eta}$ = -0.39, p = .02) and obesity(${eta}$ = -0.70, p<.0001) was indicated to be low in number of DMFT pieces compared to normality. And to conclude, obesity(body mass index) and dental caries(DT, DMFT) were found to have negative correlation. A significant result was indicated even after adjusting confounding variables.