A mobile communication system in which packets are transferred between network nodes for handing-over is disclosed. The mobile communication system comprises a packet data classifying unit that classifies packets based on a required transferring period; and a transfer controlling unit that transfers the classified packets, classification by classification, from an original network node to a destination network node. The packet data classifying unit classifies packets into a real-time-packet to be transferred in a real time manner or a non-real-time packet to be transferred in a non-real time manner.