The intake of processed foods containing high levels of sugar increases the incidence of chronic diseases, including obesity, diabetes, and metabolic syndrome. Limiting sugar intake is important for a healthy life at all ages. Therefore, this study analyzed food sources and sugar intake by the different age groups based on the 7th Korea National Health and Nutrition Examination Survey (KNHANES). We used 24-hour recall survey data to investigate the daily sugar intake and the major food groups and main dishes contributing to sugar intake. The mean sugar intake was 58.9-66.8 g/day. The three major food groups contributing to sugar intake were fruits (15.2-19.9 g/day), beverages (10.7-12.4 g/day), and milk and milk products (7.6-7.8 g/day). Teas and other non-alcoholic beverages (14.7-17.3 g/day), fruits (12.5-16.2 g/day), and dairy products (7.0-7.6 g/day) were the major food groups that contributed to the sugar intake. Carbonated drinks, apples, and milk were the top sources of sugar intake in each group. In conclusion, the sugar intake of Koreans is mainly from carbonated drinks, fruits, and milk. These results provided the basic data for nutrition education and nutrition program development according to the different age groups of the Korean population.