The role of the private security industry as a co-producer of public security is becoming more important than ever due to the government's privatization policy and the implementation of the local self-government system. However, excessive competition, high small size, vertical organizational structure, and emotional labor from the customer service process are acting as factors hindering the security guards' enthusiasm for the job and customer orientation. Therefore, this study aimed to find a way for private security personnel to voluntarily increase customer orientation, based on the results of previous studies, to examine the effect of the leader-member exchange relationship (LMX) of private security organizations on customer orientation as a mediator of job enthusiasm. The purpose of this study is to elucidate the causal relationship focusing on the effect. In this study, private security guards working in private security companies(55 places) located across the country were set as the population, and then a questionnaire survey(2021.6.21.~7.28) for the collected data(762 copies), frequency analysis, reliability analysis, exploratory factor analysis, correlation analysis, multiple regression analysis, and mediating effect analysis were performed using the statistical program SPSS 22.0. As a result of the study, first, in the relationship between LMX and job enthusiasm, emotional bonding and contribution of LMX had a positive (+) effect on the vitality of job enthusiasm, and LMX's contribution had a positive (+) effect on commitment of job enthusiasm. Second, in the relationship between LMX and customer orientation, LMX's emotional bond and contribution have a positive (+) effect on customer-oriented service satisfaction, and LMX's emotional bond and contribution have a positive (+) effect on customer-oriented satisfaction of customer needs. LMX's emotional bond and contribution have a positive (+) effect on customer-oriented understanding of customer needs. Third, in the relationship between job enthusiasm and customer orientation, the vitality and dedication of job enthusiasm have a positive (+) effect on customer-oriented service satisfaction, and the vitality and dedication of job enthusiasm have a positive (+) effect on customer-oriented customer needs satisfaction, and the vitality and dedication of job enthusiasm have a positive (+) effect on customer-oriented understanding of customer needs. Fourth, in the relationship between LMX and customer orientation, the vitality and dedication of job enthusiasm plays a mediating role in the relationship between service satisfaction, customer needs satisfaction, and understanding customer needs, which constitute customer orientation only in the contribution of LMX. Reflecting these research results, first, private security organizations need to improve their vertical organizational structure. Leaders need to improve the environment so that security guards can voluntarily participate in their duties and do their best for customers by expressing and accepting individual opinions through continuous communication with security guards. Second, it is necessary to rethink the motivation so that the security guards themselves can participate in customer orientation with dedication and vitality to the organization by configuring an autonomous work environment to form a mutual trusting relationship between the leader and members.