The Service sector has increased dramatically in importance over the last decade, both internationally and in the Korea. Deregulation of services, growing competition, fluctuations in high quality demand, and the application of the Information Technologies are presenting a considerable challenge to service companies. In gas or oil companies are exposed to foreign competitions, price and promotion competition with other companies. Usually Service Quality includes five dimensions: Reliability, Responsiveness, Assurance, Empathy, and Tangibles. Customers use these five dimensions to form their judgements of service quality, which are based on a comparison between expected and perceived service. The intention of this thesis is to study on the effect of Service Quality upon the Customer Satisfaction in gas or oil station, based on SERVQUAL.