DRIVING ASSISTANCE DEVICE, VEHICLE, METHOD, AND COMPUTER READABLE STORAGE MEDIUM

An in-vehicle driving assistance device, comprising a decision unit configured to decide whether or not to use a driving assistance function based on a travel environment of a vehicle, a notification unit configured to notify a driver of the vehicle of a guidance recommending use of the driving assistance function in a case where the decision unit decides that the driving assistance function is usable, a recording unit configured to record a reaction from the driver to the notification by the notification unit as a reaction history, and a determination unit configured to determine a mode of the notification by the notification unit based on the reaction history recorded in the recording unit.