A line detector apparatus and method on a vehicle for detecting a line on a road with a higher degree of accuracy. The vehicle includes front, right-side and left-side image capturing sensors mounted on a vehicle and respectively capture an image, including a road surface, at the front and right and left sides of the vehicle to respectively generate front, right-side and left-side images. The line detector includes a processor that calculates a line on a road as a first line from the front image, the line on the road as a second line from the right-side image, and the line on the road as a third line from the left-side image. The processor selects one of multiple mutually-different algorithms based on the first to third lines, and calculates the line on the road based on the first to third lines by using the selected algorithm.