Driving Assistance Method and Driving Assistance Device

A driving assistance method causes a controller to perform processing of making a proposal of a lane change to a passenger when an index value based on relative speed of a preceding vehicle with respect to an own vehicle is less than a threshold value and canceling the proposal of the lane change when a lane change execution condition is not satisfied. The controller performs processing including: accepting setting of the threshold value; and not presenting a lane change proposal after the proposal of the lane change is canceled depending on the travel environment until a set time elapses from a time point when the proposal of the lane change is canceled, even when the index value is less than the threshold value, and the set time is set to a longer time when the threshold value is high than when the threshold value is low.