Peer interaction and social roles have been important factors in students' academic performance. Recent work on what influences academic performance in Thailand has focused on the quality of a school, students' backgrounds, and students themselves. A few works have analyzed the correlation between social roles and students' academic achievement. Therefore, this study was designed to measure the social networks of Thai undergraduate students and analyze the relationship between their roles in social networks and academic outcomes. The data analysis was based on social network theory and permutation test. Social network theory was used to measure essential network characteristics and extract social roles. Four roles were extracted in a social network: central members, clique members, liaisons, and isolators, and analyzed a relationship between the roles and academic performance. Data was collected via questionnaires from 384 students and used to build two types of networks: friend networks and study-helper networks. A permutation test was used for statistical hypothesis testing. The results showed that 1) Being a central member positively correlates with academic performance in friend and study-helper networks. The correlation coefficients between the degree of being a central member and academic performance are also positive in all schools and both types of networks. 2) Being an isolator negatively correlates with academic performance in study-helper networks. These results indicate that a social network plays a vital role in academic performance. The results suggest that academic institutes should encourage the development of students' social networks and strengthen the networks so that students can exchange their knowledge easier and help each other in learning, leading to better academic performance.