A radio base station managing a handover source cell decides a method for achieving a handover in consideration of CSG-ID and Access Mode of a handover destination cell. A mobile communication method comprises: a step of notifying, by a radio base station HeNB#1, a radio base station HeNB#2 of CSG-ID and Access Mode of cell subordinate to a radio base station HeNB#1, when establishing an X2 connection with the radio base stations HeNB#2; the radio base station HeNB#2 managing the CSG-ID and the Access Mode of the cell subordinate to the radio base station HeNB#1; a step of deciding the method for performing the handover of the mobile station UE from the cell subordinate to the radio base station HeNB#2 to the cell subordinate to the radio base station HeNB#1 on the basis of the managed CSG-ID and Access Mode of the cell subordinate to the radio base station HeNB#1.