To make a door unlocked automatically, with no action by a person being present indoors, at the time when a person permitted beforehand to enter from outdoors pushes a call button of an interphone outdoor unit and to make an indoor unit start to enable execution of communication at the time when a person not permitted beforehand to enter from outdoors pushes the call button.

A fingerprint image pickup device 9 picking up an image of the fingerprint of a finger pushing a call button 8 is provided in an interphone outdoor unit 1. A fingerprint collating device 3 collating the image the fingerprint picked up by the fingerprint image pickup device 9 with that of the fingerprint registered beforehand is provided at a proper place in an interphone indoor unit 2 or the like. An electric lock which is locked and unlocked by an electric lock controller 19 is fitted to a door 4. The fingerprint collating device 3 outputs an unlock signal to the electric lock controller 19 when the collation of the fingerprints shows coincidence, while it outputs a start signal to the indoor unit 2 when the collation shows no coincidence.