While demands on private securities have been increase, expectations on the service quality as compensation for the investment expensive is also rising. However, private security services are in situations of not satisfying various customer\'s needs owing to insufficient special manpower, capital, and skills in spite of expected high-quality services toward customers. Therefore, this study aims to find out the causality between private security enterprises and relationship characteristics, purchasing behaviors of customers, and then searching for a marketing strategy that can provide best services to the enterprises that are confronting to limitless competitive systems by grasping customer\'s needs and necessities. For achieving this goal, the study objected to shop employees using private security enterprises after diving Cheonan City of South Chungcheong Province into South, East and East, West, and then collected 236 persons by using the convenience sampling. Regarding to research tools, this study used questionnaire having been recomposed based on previous researches home and abroad, and frequency analysis, reliability analysis, factor analysis, correlation analysis, and regression analysis were carried out data was treated by treatments by using SPSS version 18.0 statistic package for treating the data. Through above research methods and procedures, results could be gotten same as followings. First, correlations between private security enterprise\'s relationship characteristics and purchasing behaviors showed positive (+) relations, and the latter was increased as much as relationship characteristics were high. Second, as the result of analyzing correlations between private security enterprise\'s relationship characteristics and purchasing behaviors, reputation, physical features, and communication affected influences to word of mouth activities. Third, reputation and communication affected to repeated purchasing behaviors as the result of analyzing private security\'s relationship characteristics and repeat purchasing behaviors.