In road white line detecting apparatus and method, a CCD camera is installed to photograph a road surface, an edge image is generated from a road surface image photographed and outputted by the CCD camera, edge positions of a smear are detected from a region of the generated edge image which is determined on the basis of a previously detected position of a white line on the road surface, smear edges corresponding to the edge positions of the smear are generated from the generated edge image, and the present position of the white line are detected from the generated edge image from which the smear edges have been eliminated.