DRIVING ASSISTANCE DEVICE AND DRIVING ASSIST METHOD

An environmental information acquiring unit () to acquire environmental information on an environment around a mobile object, an action information acquiring unit () to acquire action information on an action of a driver of the mobile object, a calculation unit () to obtain control information for performing automated driving control of the mobile object on the basis of the environmental information acquired by the environmental information acquiring unit () and a machine learning model () that uses the environmental information as an input and outputs the control information, a contribution information determining unit () to determine contribution information having a high degree of contribution to the control information on the basis of the environmental information and the control information, a cognitive information calculating unit () to calculate cognitive information indicating a cognitive region of the driver in the environment around the mobile object on the basis of the action information and the environmental information, a specification unit () to specify unrecognized contribution information estimated not to be recognized by the driver on the basis of the contribution information and the cognitive information, and an information output control unit () to output driving assistance information necessary for driving assistance on the basis of the unrecognized contribution information specified by the specification unit () are provided.