DRIVING ASSISTANCE DEVICE

A driving assistance device that performs a notification process for notifying a driver of a risk of a collision with a preceding vehicle in cooperation with a notification device includes: an inter-vehicular distance acquisition section that successively acquires an inter-vehicular distance; a first index calculator that calculates a first risk index indicating a degree of the risk of the collision based on a traveling speed and the inter-vehicular distance; a second index calculator that successively calculates a second risk index based on a relative speed between the own vehicle and the preceding vehicle; a notification level determination section that successively determines a notification level indicating a strength of notification for notifying the risk of the collision, based on the first risk index and the second risk index; and a notification processor that performs the notification process in a notification mode corresponding to the notification level.