As International franchise, this Japanese restaurant are able to captivate the heart of sushi lovers in Medan. This can be seen from the long waiting list in restaurant and also growing numbers of the Sushi Tei outlet in Medan and also across Indonesia. Maintaining and developing customer loyalty in the midst of growing competition can be very challenging. Thus, this study is keen to know how Sushi Tei developed their customer loyalty through relationship quality. The purpose of this study is to analyze the effect of Physical Environment (PE), Communication (CN), Customer Orientation (CO), Relationship Benefits (RB), Price Fairness (PF), and Food Quality (FQ) towards Customer Loyalty (CL) through Relationship Quality (RQ) at Sushi Tei Restaurant in Medan. The study is conducted with the total of 150 respondents with the age group ranging from 18 to 60 years who have dine in Sushi Tei Medan at least twice in two years period and possess the membership card of Sushi Tei. The data generated were then being process using AMOS with Structural Equation Modelling (SEM). The results of the study show that: Physical environment show positive results but insignificant with the C.R. = 0.8652 and regression coefficient of 0.099; Food quality and relationship quality show positive results and significant with the C.R. = 4.4259 and regression coefficient of 0.5676; Customer orientation and relationship quality show positive results but insignificant with the C.R. = 1.3418 and regression coefficient of 0.1660; Customer orientation and relationship quality show positive results but insignificant with the C.R. = 0.9202 and regression coefficient of 0.1037; Relationship Benefits and relationship quality show positive results but insignificant with the C.R. = 1.4733 and regression coefficient of 0.1912; Price Fairness and relationship quality show positive results and significant with the C.R. = 2.0575 and regression coefficient of 0.2535; and Relationship Quality and customer loyalty shows positive results and significant with the C.R. = 6.5001 and regression coefficient of 0.8368.