1. A lane detecting apparatus comprising: a region of ID setup setting a region of ID including a road region of a current lane in an acquired image; a road sign verifier verifying existence of a road sign within the set region of ID; an ROI setup calculating a difference value between a lane prediction result and previous lane information when the road sign verifier verifies existence of the road sign and setting an ROI based on the calculated difference value, wherein the set ROI is an ROI from which the road sign that hampers detection of the lane and has existed within the region of ID is removed by calculating the difference value between the lane prediction result and the previous lane information to set the ROI thereby; and a lane detector detecting a lane by extracting lane markings based on the set ROI.