To provide a VPN system enhancing a communication speed in communications using a plurality of VPN tunnels.

A VPN tunnel is established between a VPN apparatus 1-1 and a VPN apparatus 1-2 (a2), and an encryption key is exchanged between the VPN apparatus 1-1 and the VPN apparatus 1-2 (a1). In the case of establishing a VPN tunnel between the VPN apparatus 1-2 and a VPN apparatus 1-3 (a4), the VPN apparatus 1-2 uses the VPN tunnel having already been established and encrypted to securely inform the VPN apparatus 1-1 about the encryption key (a3) received from the VPN apparatus 1-3 (a5). Upon the receipt of the encryption key of the VPN apparatus 1-3 from the VPN apparatus 1-2, the VPN apparatus 1-1 stores the encryption key to a communication partner dependent encryption key storage memory as the encryption key by each communication opposite party.