Evaluating from the viewpoint of customer is necessary for service, as well as from that of providers. Thus, customer satisfaction is one of important factors on evaluating service. However, how customers perceive services changes, as they get information about services. This makes it difficult to get stable customer satisfaction. Therefore, the methodology to deal with the changes is necessary. This research aims to deal with those with customers' expectation. Expectation of service is the factor with which customer satisfaction is fixed. Customers form their expectation with information about service. This paper proposes the model of service process for customers' expectation.