To provide a driving support device for a vehicle for preventing the useless acceleration or deceleration of a vehicle traveling behind a vehicle group.

A driving support device 100 for a vehicle is provided with a vehicle group traveling state acquisition means 11 for acquiring information related with the traveling state of a vehicle group C; a vehicle group traveling environment acquisition means 12 for acquiring information related with the traveling environment of the traveling direction of the vehicle group; a vehicle group speed prediction means 13 for predicting the transition of the vehicle group speed based on the traveling state and the traveling environment; and a speed control means 14 for controlling its own vehicle speed based on the transition of the vehicle group speed predicted by the vehicle group speed prediction means 13.