According to an embodiment, a driving assistance device includes a recognizer configured to recognize a surrounding situation of a vehicle, a driving controller configured to control at least steering of the vehicle on the basis of the surrounding situation recognized, a receiver configured to receive an operation of an occupant of the vehicle, and an output controller configured to cause an output to output a traveling state of the vehicle. The driving controller causes a lane change of the vehicle to be made when a receiver receives an instruction for allowing the vehicle to make the lane change and a condition in which the lane change is made is satisfied. The output controller causes the output to output information about the lane change when the lane change has not been started even though a first prescribed time period has elapsed after the receiver received the instruction.