A method for diagnosing cancer comprising detecting ROBO1 protein is disclosed. In addition, a method for treating a disease caused by abnormal cell growth comprising administrating an antibody that binds to ROBO1, as well as a pharmaceutical composition, a cell growth inhibitor and an anticancer agent comprising an antibody that binds to ROBO1 as an active ingredient are disclosed. Further, a method for inducing cell damages in a ROBO1 expressing cell and a method for inhibiting the growth of a ROBO1 expressing cell by bringing a ROBO1 expressing cell into contact with an antibody that binds to ROBO1, are disclosed. Furthermore, a method for monitoring progression of hepatitis by detecting ROBO1 protein is disclosed.
