DRIVING ASSISTANCE METHOD AND DRIVING ASSISTANCE DEVICE

A driving assist device (1) comprises a camera (10) that detects a presence of another vehicle ahead of a host vehicle and a controller (20) that sets a detection field of the camera (10). The controller (20) determines that another vehicle has cut in front of the host vehicle if a degree to which the other vehicle has entered into the detection field exceeds or equals a first prescribed value when the host vehicle is traveling, and determines that the other vehicle has cut in front of the host vehicle if the degree exceeds or equals a second prescribed value that is smaller than the first prescribed value when the host vehicle is stopped.