In a video-conferencing system using a mobile terminal device and a method for implementing the same, by connecting mobile terminal devices, which have a wireless LAN module, a camera module and a video conference application program, to each other by a wireless LAN and by performing communications using wireless LAN Adhoc mode between the mobile terminal devices, the cost spent implementing a video-conferencing system is reduced and the free mobility can be secured in a place where people frequently move such as a building office, a warehouse of a distribution company or a temporary event place.