The growth in services has focused issues of service quality both for commercial enterprises and across a range of public services and government institutions. The education sector, in particular, has undergone radical change to meet the needs of its varied constituents. This paper examines key issues in internal service, customer satisfaction, service quality, relational commitment as they apply in one particular education sector. The purpose of this study is to analyze effect of internal service on customer satisfaction, educational service quality. First, In the dimension of internal service, many factors affect internal customer's evaluation for overall satisfaction. They are categorized as five factors; tangibles, reliability, responsiveness, assurance, empathy. The results of this study supported the proposed conceptual framework overall. Therefore, we identified that internal service quality is the antecedent of an internal customer satisfaction, and the consequent variables of an internal customer satisfaction are educational service quality, external customer satisfaction. The major findings of this study are summarized as follows. First, some factors(tangibles, reliability, responsiveness, assurance, empathy) affected positively internal customer satisfaction. Second, external service quality affected positively educational service quality, external satisfaction. In other words, the more internal customers have experienced internal service, the higher internal service quality deliver educational service quality.