A lane recognizing image processing system for recognizing lane markings laid on a driving road for motor vehicles includes a lane marking candidate point extraction means (20) for extracting lane marking candidate points (C) from an image (G) taken by an image pickup means (10) mounted on the motor vehicle, and a lane recognizing means (30) for recognizing a lane defined on the road on the basis of set of the lane marking candidate points (C). The lane recognizing means (30) includes a lane marking candidate point position converting means (31) for recognizing as lane marking candidate point positions the positions of the lane marking candidate points (C) transformed onto a straight line extending toward a null point.