Humans, social animals, begin their lives by forming relationships with others. Therefore, various studies have been conducted on the formation, maintenance, and termination of human relationships. Online relationships are similar to offline relationships. Accordingly, various studies have been conducted on forming, maintaining, and ending (disrupting) interpersonal relationships online. However, in addition to forming, maintaining, and disconnecting relationships, there is another function called hiding on mobile messengers or SNSs (Social Network Services). Despite the fact that the function is actively used on mobile messengers, there is a lack of research on why mobile messenger users use the function. This study was conducted to explore predictors of using the hiding function on mobile messengers. The analysis results are as follows. Among the three predictors, including relationship quality, privacy concerns, and perceived blocking, the factor that had a significant impact on concealment intention was privacy concerns. In addition, after dividing the groups into users who were using the hiding function and those who were not using it, the results of analyzing the differences between the two groups showed that privacy concerns had a significant impact on the hiding function among users who were using the hiding function. In the analysis of differences by gender, the effect of privacy concerns on intention to conceal was significant only for women, and no significant relationship was found for men. These results show that the reason mobile users use the hiding function is because they are concerned about their privacy. Additionally, it can be seen that women are more likely to use the hiding function than men.