A vehicle system (100) includes a driving operation information acquisition unit (15) arranged to acquire a value indicative of a degree to which a driving operation is carried out by a driver, a driving state switching unit (16) arranged to switch a driving state of a vehicle between a first driving state and a second driving state based on a relationship between the value indicative of a degree to which a driving operation is carried out by a driver and a first threshold, the first driving state including at least one of an autonomous driving state where traveling of the vehicle is controlled by using a traveling plan generated based on peripheral information relating to the vehicle and map information provided in advance for the vehicle and a cooperative driving state where the vehicle is allowed to travel with a vehicle control based on the peripheral information relating to the vehicle and the driving operation carried out by a driver working in tandem with each other and the second driving state allowing the driving operation carried out by a driver to be reflected in the traveling of the vehicle, and a notification unit (7) arranged to notify a driver of a relationship between the first threshold and a state of the value indicative of a degree to which a driving operation is carried out by a driver.
