The present invention relates to a system for detecting a region of interest about a tilted line including: an image acquisition unit configured to acquire a front image by photographing a front of a vehicle; an image processing unit configured to divide the front image in a pixel unit of a row and a column and shift the front image by one pixel in a left or right direction in each row or in an upper or lower direction in each column until a region of interest (ROI) appears in a straight line in one direction; and a control unit configured to calculate coordinate values of the pixels forming the straight line in one direction to determine the tilted line of the region of interest, when the straight line in one direction appears in the region of interest as the shifted result.