Disclosed is a mobile communication system which includes user equipment, radio base stations which communicate with the user equipment, and an upper level apparatus which communicates with the radio base stations. Each of the radio base stations includes a control unit and an inter-node communication unit. The control unit hands over a communication with user equipment to a hand-over target base station. The control unit prepares a forwarding packet which includes data addressed to the user equipment and is not transmitted and delay value identification information for specifying a delay value of the data that is not transmitted at the time of a hand-over. The inter-node communication unit transmits forwarding packets to a hand-over target base station.