Driving support device for vehicle and method for the same

A control device in one aspect of the present disclosure includes a vehicle information acquisition unit, an obstacle information acquisition unit, and a sudden braking detection unit, and controls a warning information transmission unit to transmit, to an other vehicle, warning information including obstacle information when a sudden braking is performed by a subject vehicle. When receiving the warning information from the other vehicle, a target vehicle determination unit confirms that the other vehicle is a warning target vehicle, and a risk calculation unit calculates a collision risk of the subject vehicle to collide with an obstacle, and a collision avoidance unit performs a collision avoidance control according to the calculated collision risk.