An Optical Virtual Private Network, hereafter referred to as OVPN, terminating device connected to a user's device, characterized by comprising: a plurality of converting sections (33, 34), which are disposed so as to correspond to plural different first signal formats, for converting a first signal format to and from a second signal format under conditions in which the first signal format which is used by a user's device which joins an OVPN and a second signal format which is used in the OVPN are different from each other; a registering section for registering at least a first signal format type which is sent from the user's device so as to be used in the user's device together with an IP address of the user's device and a VPN identifier; a notifying and selecting section for notifying the registered contents to other OVPN terminating device which controls the device which receives the calling connection request from the user's device when the calling connection request arrives from the user's device and selecting the first signal format type which can be used in the user's device handled between other OVPN terminating device and the own OVPN terminating device commonly according to the registered contents; a retrieving section (30, 80) for retrieving information indicating a vacancy of the converting section for the converting operation both in the own OVPN terminating device and other OVPN terminating device when the first signal format type which is selected by the selecting section is different from a second signal format type; and a selecting section (30, 80) which selects at least either one of the converting section for the converting operation which is not occupied for the own OVPN terminating device and other OVPN terminating device according to the retrieving result by the retrieving section. a plurality of converting sections (33, 34), which are disposed so as to correspond to plural different first signal formats, for converting a first signal format to and from a second signal format under conditions in which the first signal format which is used by a user's device which joins an OVPN and a second signal format which is used in the OVPN are different from each other; a registering section for registering at least a first signal format type which is sent from the user's device so as to be used in the user's device together with an IP address of the user's device and a VPN identifier; a notifying and selecting section for notifying the registered contents to other OVPN terminating device which controls the device which receives the calling connection request from the user's device when the calling connection request arrives from the user's device and selecting the first signal format type which can be used in the user's device handled between other OVPN terminating device and the own OVPN terminating device commonly according to the registered contents; a retrieving section (30, 80) for retrieving information indicating a vacancy of the converting section for the converting operation both in the own OVPN terminating device and other OVPN terminating device when the first signal format type which is selected by the selecting section is different from a second signal format type; and a selecting section (30, 80) which selects at least either one of the converting section for the converting operation which is not occupied for the own OVPN terminating device and other OVPN terminating device according to the retrieving result by the retrieving section.