To improve power use efficiency in a standby state and at the time of absence by feeding power only to a line interface part in the standby state and preventing power from being fed to a control part and a sound, image main unit part and a monitor for incoming calls in the standby state, on a holiday and at the time of absence in time out of business hours.

The communication of sound, an image and data between a video conference device 1 and another video conference device is executed by using the B/H channel of an ISDN network 2 and the line interface part 10 executes communication by using a D channel. When the line interface 10 receives a call control message, the call is returned to the ISDN network on holiday and at the time of absence. The call is cut since an opposite terminal is called at preset. A notice is given to a second power source part 15 from the line interface part 10 through a release completion message and power feeding is stopped. In the case of the reception during a time band when communication is possible, the notice is given to the second power source part 15 from the line interface part 10, power is fed to the video conference device and communication is realized.