SAFE DRIVING ASSISTANCE DEVICE

A safe driving assistance device includes a region setting section that sets a collision risk determination region used for determining presence or absence of a collision risk of a host vehicle, and a determination section that determines a collision risk between the host vehicle and another vehicle using a host vehicle collision risk determination region, another vehicle collision risk determination region, and environment data. The host vehicle collision risk determination region of the host vehicle is set based on travel data of the host vehicle, a vehicle specification of the host vehicle, and the environment data obtained by the host vehicle. The other vehicle collision risk determination region is obtained by a vehicle-to-vehicle communication device. The other vehicle collision risk determination region is the collision risk determination region of the other vehicle as a collision risk determination target with the host vehicle set by the other vehicle.