This study aimed to provide basic data for enhancing the sense of well-being of college students by analyzing the major factors affecting the happiness of college students using random forest, a machine learning technique. To do this, data from 5,299 college students’ responses from the first to third year survey of ‘Korean Education & Employment Panel (KEEP)Ⅱ’ were used. A total of 105 variables including demographic, family and school environmental, and personal characteristics variables were included in the analysis. The main results are as follows. First, the personal, family, and school variables were ranked in the top 20. It means that college students’ happiness was affected compositively by individual, family, and school-related factors. Second, ‘the degree of satisfaction about current economic situation’ had the highest importance index most among the 105 variables. Third, satisfaction with college life, college, major, and college infrastructure were major factors influencing college students’ happiness. Fourth, the variables related to health, such as perceived health status and academic stress were significant factors, as well. Lastly, many variables measured during high school years were included the top 20. This result showed that college students’ happiness was affected by not only their current situation, but also their accumulated experience over the years.