A driving assistance device includes a speed zone computation unit configured to compute a speed zone of the host vehicle having a possibility that the host vehicle will come into contact with the mobile object when progressing in the progressing direction, based on the mobile object information set by the mobile object information setting unit; a target speed computation unit configured to compute a target speed of the host vehicle based on a speed zone; and a target speed profile creation unit configured to create a target speed profile for decelerating the host vehicle from the current speed to the blind spot entry target speed, based on a blind spot entry target speed which is the target speed of the host vehicle at the time of entering a place forming the blind spot, a current speed of the host vehicle, and a target acceleration for deceleration.