A driving assistance device includes: an information receiver configured to receive information required for estimation of an other vehicle predicted route which is a predicted traveling route of another vehicle, from the other vehicle through wireless communication; and an electronic control unit configured to acquire a host vehicle predicted route which is a predicted travel route of a host vehicle, acquire the other vehicle predicted route; provide a warning to a driver of the host vehicle when the host vehicle predicted route and the other vehicle predicted route intersect each other, and prohibit the electronic control unit from providing the warning when determining that a predetermined parking lot traveling condition is satisfied, the predetermined parking lot traveling condition being a condition that is satisfied when the electronic control unit determines that the host vehicle is likely to be traveling in a parking lot.