The purpose of this study is to investigate the influence of parasocial interaction on the online shopping mall loyalty. Specifically, this paper focuses on the situation in which a celebrity is utilized as a main model or a owner in online shopping mall specialized in apparel to enhance the loyalty of customer. And it also examines the moderating effect of product knowledge(high vs. low) and regulatory focus(promotion focus vs. prevention focus) on the causal relationship between parasocial interaction and online shopping mall loyalty. The results of this study are as follows. First of all, parasocial interaction has a significant influence on online shopping mall loyalty positively. Second, when parasocial interaction is high, the response of consumer with low product knowledge is more positive about the online shopping mall loyalty than high one, whereas if parasocial interaction is low, consumer who has low product knowledge responds less positively to the online shopping mall loyalty than high one. Third, prevention focus in regulatory focus has a more positive effect on online shopping mall loyalty if parasocial interaction is high, however, promotion focus in regulatory focus has a more positive effect on online shopping mall loyalty when parasocial interaction is low. Therefore, it is supported that product knowledge and regulatory focus have interaction effects on the influence of parasocial interaction on the online shopping mall loyalty. Finally, the implications, limitations and future study directions based on the study results are discussed.