DRIVING ASSIST METHOD AND DRIVING ASSIST DEVICE

A driving assist device includes a camera and a controller. The camera detects the presence of another vehicle ahead of a host vehicle. The controller sets a detection field of the camera. The controller 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, or 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.