The present disclosure relates to a pharmaceutical composition for treating or preventing cancer, a pharmaceutical composition for immune-enhancing, a method of screening of anti-cancer agent, and a method of providing information necessary for analysis of cancer prognosis. According to the present disclosure, cancer can be effectively prevented or treated using a CNTN4 inhibitor, and the immunity of subject can be enhanced. In addition, the present disclosure is very useful because it can effectively select new anticancer drug candidates by determining the activity or expression of CNTN4 and can provide information necessary for diagnosing and predicting cancer prognosis.