An automotive lane deviation prevention (LDP) apparatus includes a control unit connected to a yawing-motion control actuator for LDP control purposes. The control unit determines, based on information regarding a lane marking line detected based on a picture image in front of a host vehicle, whether the host vehicle is in a state F.sub.LD.noteq.0 where there is an increased tendency for the host vehicle to deviate from the driving lane. The control unit executes, based on a state Fdw.noteq.0 where the host vehicle is traveling on predetermined irregularities formed on or close to the lane marking line and the information regarding the lane marking line, vehicle yawing motion control by which the host vehicle returns to a central position of the driving lane, in a lane-marking non-detecting state F.sub.camready=0 where the lane marking line is out of an image pick-up enabling area.