The purpose of this study was to investigate the mediating roles of the relationship quality and the switching cost during the processing of effects of service quality on the service loyalty in the beauty industry. Service quality factors were defined as the interaction quality, the outcome quality and the physical environment quality. The relationship quality were defined as the satisfaction and the trust of customer. Amos was used to analyze the research hypotheses and the proposed model. All research hypotheses were adopted. The empirical results were as follows; Service quality influenced positively on the relationship quality, and then the relationship quality yielded the service loyalty. Also the relationship quality influenced positively on the switching cost and then the switching cost influenced positively on the service loyalty. Each service quality dimension had a significant effect on the satisfaction, the trust and the relative importance of service quality dimensions on the satisfaction, the trust followed the order of the interaction quality, the outcome quality and the physical environment quality.