To make it possible to constantly watch an LCD monitor video in the wide direction of a visibility angle without regard to the installing situation/ using situation of an interphone master set provided with an LCD monitor.

In an interphone system by which a user can speak while looking at the face of a visitor by displaying the video of the visitor, which is picked up by a camera provided at a slave set at an entrance, on the LCD monitor 2 provided at the interphone master set M installed indoor, the LCD monitor module 1 of the monitor 2 is fitted to the interphone master set main body 4 of the master set M in an attachable and detachable manner. The module 1 is fitted to the main body 4 with the module 1 upside down in accordance with the angle of visibility in a horizontal direction being asymmetrical when the monitor 2 is used to be long vertically.