This study attempts to understand perceived switching barriers of customers and fashion stores service quality as a core of store loyalty. Medium variations of switching barriers are interpersonal relationships, attractiveness of alternatives and switching costs. Date were collected from 485 subjects who finished their shopping with a self-administered questionnaire. The results were as follows: 1. Classified service quality of clothing stores into 4 ways: VMD of stores or atmosphere, store policy which are involved in store service, sales persons respond and sales persons conviction which are involved in sales service. 2. Service quality of fashion stores is related with switching barrier medium variations. 3. Service quality have an influence on switching barrier medium variations. Its mutual influences increase switching barriers and it gets to be related to the store loyalty. 4. Compared influences of variations to store loyalty between the H department store and the L department store which are research objects. The main difference is that the H department store evaluated personal relationships among service quality, customers and sales persons high compared with the L department store. As the results showed, service quality consists of store service of nonpersonal service area and sales service of personal service. Service quality is related with interpersonal relationships, attractiveness of alternatives and switching costs. It also affects switching barriers and store loyalty.