A communication device, which is mounted on a vehicle or installed at the roadside, and which is adapted to perform inter-vehicle communication between in-vehicle communication devices (1~N) mounted to vehicles, or which is adapted to perform road-to-vehicle communication between an in-vehicle communication device (1∼N) and a road-side communication device installed at the roadside, characterised by comprising: an in-vehicle radio section which is adapted to broadcast its own device position information, and is adapted to receive the device position information of another vehicle from the communication devices of other vehicles; a surrounding communication device information table which is adapted to store other communication device position information received from the other communication device and the time of the position information; a transmission destination determining section which is adapted to control the storage content of the surrounding communication device information table, and which, when receiving transmission destination position/area information representing a position or area of a transmission destination communication device, is adapted to determine, on the basis of the transmission destination position/area information and of the storage content of the surrounding communication device information table, a communication device with which communication is to be performed, and is then adapted to return the determination result as a transmission destination setting signal; and an in-vehicle communication control section which is adapted to transmit its own device position information at every predetermined period from the in-vehicle radio section, which, when receiving the position information from the other communication device, is adapted to store the received position information in the surrounding communication device information table via the transmission destination determining section together with the time of the position information, and which when performing transmission and reception of data information with a communication device whose position or area is designated, is adapted to output the transmission destination position/area information to the transmission destination determining section, and is adapted to perform, via the in-vehicle radio section, communication with the communication device designated by the subsequently transmitted transmission destination setting signal; and the radio communication channel used in the radio signal and that transmitted and received the data information is different from the radio communication channel that transmitted and received the device position information. an in-vehicle radio section which is adapted to broadcast its own device position information, and is adapted to receive the device position information of another vehicle from the communication devices of other vehicles; a surrounding communication device information table which is adapted to store other communication device position information received from the other communication device and the time of the position information; a transmission destination determining section which is adapted to control the storage content of the surrounding communication device information table, and which, when receiving transmission destination position/area information representing a position or area of a transmission destination communication device, is adapted to determine, on the basis of the transmission destination position/area information and of the storage content of the surrounding communication device information table, a communication device with which communication is to be performed, and is then adapted to return the determination result as a transmission destination setting signal; and an in-vehicle communication control section which is adapted to transmit its own device position information at every predetermined period from the in-vehicle radio section,