Fully meshed virtual paths obtained with smaller number of settings, thus facilitating expansion of VPN service. A communication device in a virtual private network (VPN) having a VPN accommodation function for connecting an intra-organization network or inter-organization network through the Internet includes; a first means for generating a VPN address, a format of which includes both a VPN number for uniquely identifying a VPN in a certain scope and a closed address used in an organization or among organizations, either converting a packet header into a header having the above-mentioned VPN address or adding the above-mentioned VPN address to a packet header for transmission; and a second means for on receiving the packet having a header of the VPN address format, either converting the received packet into a packet format equivalent to an original packet format or removing a header having VPN address format.