To transmit a series of data to a destination without failure even when a data communication device utilizing a public radio communication system to send the continuous data leaves the service zone.

A hard disk 16 tentatively stores data S15 that cannot be sent from a video camera 11 under the control of a system control circuit 31 for a period when a service zone identification section 24 identifies that the radio communication device stays outside the service zone, and data S 16 having been stored in the hard disk are transferred to a destination when the identification section 24 judges that the device has moved into the service zone. Furthermore, the device is provided with a residual capacity alarm section 32, which prevents such a situation that the video camera becomes suddenly out of service because the residual capacity of the hard disk expires when the device stays outside the service zone for a long time.