A relay server which is connected to a LAN and which can communicate with a relay server in a different LAN, includes: an account information registering unit that stores information on client terminals connected to the LAN; a relay group information registering unit that stores relay group information; a shared resource information registering unit that stores shared resource information; a check unit that checks whether the client terminals stored in the account information registering unit can be accessed; a relay group information notifying unit that updates the relay group information and transmits a change notification of the relay group information to the relevant relay server; and a shared resource information notifying unit that updates the relevant shared resource information and transmits a change notification of the shared resource information to the relevant client terminal which is stored in the account information registering unit.