DRIVING SUPPORT DEVICE

PROBLEM TO BE SOLVED: To secure safety by appropriately providing driving support according to a driver's physical state affecting safe driving of an own vehicle.SOLUTION: A driving support ECU 22 of an own vehicle 2 calculates a positional relationship between the own vehicle 2 and a surrounding vehicle 4 on the basis of positional information on the own vehicle 2 and positional information on the surrounding vehicle 4, if an alarm operation condition in which an awakening level of a driver does not satisfy a prescribed determination criterion is fulfilled. If the surrounding vehicle 4 is a preceding vehicle, the driving support ECU 22 transmits alarm command information to the surrounding vehicle 4 via vehicle-to-vehicle communication for instructing to light or blink a brake light 28. If the surrounding vehicle 4 is a following vehicle, the driving support ECU 22 transmits the alarm command information to the surrounding vehicle 4 via the vehicle-to-vehicle communication for instructing to light or blink a headlight 30. A driving support ECU 38 of the surrounding vehicle 4 receiving the alarm command information, therefore, executes alarm operation for alerting the driver of the own vehicle 2.