Service quality has become an important factor to meet customer satisfaction in the food service industry where competition is getting severe. Organizations are focused upon strengthening customer loyalty through customer satisfaction. Therefore, this study, taking customers as subjects, is intended to analyze factors affecting customer loyalty, on the basis of service quality expectations and service quality satisfaction. In doing so, the analysis has been done with 232 customers who are purchasing service from the food services industry, for general information, and service quality expectation, service quality satisfaction, and overall satisfaction. The results of the study are as below. 1) From a factor analysis, the service quality expectation level of customer has been categorized into 4 factors, which are named `General management`, `Food`, `Reliability` and `Reputation`. 2) From the factor analysis, the service quality satisfaction level of customer has been categorized into 6 factors, which are named `Employee attitude`, `Food`, `Reliability`, `Atmosphere`, `Reputation` and `Price`. 3) After classifying customers into 3 groups according to two criteria- "will buy the service again" and "will suggest to others", a comparison has been done for the service quality expectation dimension of customers by each customer group. The result shows that the group having both the "will buy the service again" and "will suggest to others" criteria, that is, with higher customer loyalty, tend to have higher point than other group in factors of `Food`, `Reliability`, `Reputation`(p<.05). 4) As per the dimension of customer`s service quality satisfaction level, factors like `Employee attitude`, `Food`, `Reliability`, `Atmosphere`, `Reputation`, and `Price` have shown differences according to each loyalty group(p<0.001). 5) Customers` overall satisfaction level according to each customer loyalty group has been found to be more important for the group having a higher loyalty level(p<.001). 6) From the discriminant analysis with employing judging variables, such as the customer`s service quality expectation level, service quality satisfaction level and general satisfaction level, customer loyalty groups have been identified as accurately as 68.9% of the explanatory power. (Korean J Community Nutrition 5(2) : 225~235, 2000)