As the use of smartphone has rapidly spread into the current society, the mobile instant messenger applications such as Kakaotalk, Tiktok, and Line have become an indispensable part of our daily lives. While, the mobile instant messenger has brought us many positive changes, social problems stemming from the dependency on the mobile instant messenger has been occurred. The dependency of the mobile instant messenger can negatively affect daily lives and lead to stress or addiction. Therefore, it is very important to examine how we can prevent such dependency and addiction. In this respect, the purpose of this study is to investigate determinants impacting on the mobile instant messenger dependency, barrier of living, and intention to digital break. The statistical analysis of survey results shows that enjoyment, identity, relationship commitment, critical mass and ease of use are significantly related to mobile instant messenger dependency, while media richness is not significantly related. Mobile instant messenger dependency have a positive effect on barrier of living, which then has a positive effect on digital break. Lastly, the moderating effect of perceived risk is significant. This research suggests theoretical and business implications to prevent mobile instant messenger dependency.