This paper aims to investigate the adjustment effect of switching barriers on customer retention in mobile telecommunication services. The detailed factors regarding switching barriers are classified based on the related literatures. Furthermore, the hierarchical regression analysis is used to analyze the extent to which the factors affect customer retention. The main contribution of this paper is to focus on switching barriers and theirs relationships with customer retention rather than customer satisfaction on early studies. The results are as follows: First, among the factors of switching barriers, switching costs, such as continuity cost and contractual cost, interpersonal relationship, and attractiveness of alternatives are key factors in determining customer retention. Second, continuity cost and interpersonal relationship have an adjustment effect between customer satisfaction and customer retention. The findings can help the mobile operators establish a customer-oriented strategy by identifying a few key factors strengthening the linkage with customers.