Customer loyalty is a competitive tool for companies. Related companies depend on the loyalty of their customers, and the restaurant business is no exception. Customer loyalty has played an important role in achieving competitive advantage. The services provided must be of high quality, including responsiveness, giving, assurance, empathy, and physical evidence. This study shows the importance of service quality and Customer Loyalty to 31 Pare House Restaurant Medan, as well as the impact that can be caused by effective service quality on customer evaluation entire restaurant experience. This study discusses 31 Pare House Medan Restaurants which have been operating for more than 10 years in the culinary and restaurant industries. In this study, 31 Pare House Restoran Medan has chosen to represent competitive companies, leading to those who have good service quality. The purpose of this study is to know the effect of service quality on customer loyalty. This research was conducted by collecting data from questionnaires 30 espondents using simple random sampling techniques with quantitative research methods. Based on the results of Z-test calculations for service quality variables and customer loyalty variables Where Zcount is greater than Ztable, it means that there is a significant positive and significant effect on service quality on customer loyalty 31 Pare House Restaurant Medan. The R square value is 0.537. This means that the store atmosphere of consumer behavior variables is 53.7% while the rest is determined by other factors 46.3% in addition to this study.