The present disclosure is based on the discovery that the inhibition of KIRREL2 activity or expression significantly inhibits the development, growth, invasion, and metastasis of cancer. The present disclosure provides a pharmaceutical composition for treating or preventing cancer, comprising KIRREL2 inhibitor. In addition, the present disclosure provides a pharmaceutical composition for immune-enhancing, comprising KIRREL2 inhibitor. Furthermore, the present disclosure provides a method of screening of anti-cancer agent using KIRREL2, and a method of providing information necessary for analysis of cancer prognosis using KIRREL2.