A driving assistance device includes a driving situation acquisition unit that acquires driving situations of vehicles that may collide with each other, a driving characteristics acquisition unit that acquires driving characteristics of drivers of the vehicles, a driving action determination unit that determines driving actions that allow the vehicles to avoid collision with each other in the driving situation acquired by the driving situation acquisition unit and that match the driving characteristics acquired by the driving characteristics acquisition unit, and a driving action instruction unit that instructs the vehicles about the driving actions determined by the driving action determination unit.