The present invention provides a radio network system including a mobile station that leads in determining whether handover can be executed or not, wherein the handover is for switching a handover origin radio base station to a handover destination radio base station, wherein the handover destination radio base station reserves resources required for the handover based on a handover request from the mobile station and information on the mobile station required for the handover, and establishes a user plane path for transferring user information between itself and the handover origin node B.