This research is to figure out how interpersonal relationships among the foodservice industry affected customer satisfaction and retention. Marketing strategy methods could be indicated to bear fruit in the food-industry based on this research. First, the properties of each factor related interpersonal relationship of foodservice industry, customer satisfaction and retention were obtained from previous studies. Second, interpersonal relationship was applied as an independent variable, retention between customers and the foodservice industry as a consequent variable and customer satisfaction as a parameters. The result reached through convergent validity came to satisfy all variables. Third, it was strongly maintained that the higher interpersonal relationship was, the more satisfied customers were and that the more satisfied customers were, the stronger retention was. It was shown that customers would repurchase and had strong loyalty to a certain enterprise if its services satisfied them and met their expectations.