Intercom system for collective housing

An intercom system for an apartment house according to the invention includes room units (10A, 10B) which are installed in respective rooms of the apartment house, and a control unit (20) which is connected to the room units (10A, 10B) of the respective rooms via an intercom line (L1) so as to be capable of communicating therewith, and is capable of communicating with an external server (S) via an external communication network. The control unit (2) acquires, based on a request signal transmitted from the room unit (10) via the intercom line (L1), predetermined information corresponding to the request signal from the external server (S) via the external communication network, and transmits the acquired predetermined information via the intercom line (L1) to the room unit (10) which transmitted the request signal.