In hospitality industry, service quality is one of the crucial factors in determining customer purchase decision. Service needs to be good because when customer is comfortable and happy with the service experience, the probability of future purchase decision will increase. This research is meant to find whether service quality (variable X) have influence on purchase decision (variable Y) at Hee Lai Ton Restaurant Medan.The research is using convenience sampling as it enables obtaining information quickly and efficiently from the member of population who happen to be available and is willing. In this case, the writer took 92 respondents to represent the customers who visit Hee Lai Ton Restaurant Medan on May 2019.The data analysis showed several test result. In correlation test, there is a strong positive correlation between service quality and purchase decision. From Determination test, service quality contributed to the purchase decision at Hee Lai Ton Restaurant Medan by 41%. The result showed linear regression equation is Y = 20,916 + 0.593x. Therefore, the research concluded that there is an influence of service quality on purchase decision at Hee Lai Ton Restaurant Medan.