A home agent in a mobile Internet Protocol version 6 (IPv6) network system. The home agent is constructed with a home address table including home addresses of a plurality of mobile nodes and binding cache entry indexes corresponding to the home addresses, a next-hop entry table including a plurality of next hop entries mapped to care-of addresses of the mobile nodes, a binding cache entry table comprising a plurality of binding cache entries mapped to the binding cache entry indexes, and a packet processor. When a source address of a packet received by the home agent is included in the home address table in a state where forwarding direction information included in the packet received by the home agent differs from set forwarding direction information, the packet processor encapsulates and forwards the packet received by the home agent using a binding cache entry that is mapped to a binding cache entry index corresponding to the source address included in the home address table.