To provide an electronic apparatus which does not have an idle terminal and a wasteful space, organizes a compact sized cage, has general-purpose properties in adaptability in relation to each system scale, is not troublesome, and can endure a long-term usage, and to provide a connection method of an interphone using the electronic apparatus.

This electronic apparatus, where a printed plate board is placed in a body and a cover is engaged with the body for organizing a cage, is formed by making the printed plate board engaged with the body and by providing an engagement material for making the cover engaged with the body. Three kinds of signal lines, an image line, a communication line, and a control line are used. Those three kinds of lines are branched on the way to each house. In such wiring system for the connection of an interphone, following connection method is adapted. That is to say, each house is equipped with a switch box, an electronic apparatus with a terminal part is arranged in the switch box, only the image line among the three kinds of signal lines is connected to the terminal part of the electronic apparatus.