A method and apparatus for outputting three-dimensional (3D) lines. The apparatus acquires a first image and a second image including lines on a road, generates, based on a first feature map acquired from the first image, a line probability map representing a probability that a pixel point of the first feature map belongs to the lines, calculates matching information of the first image and the second image based on the first feature map and a second feature map acquired from the second image, predicts depth values of the lines using the line probability map and the matching information, detects the lines based on the line probability map, generates 3D lines based on the detected lines and the depth values of the lines, and outputs the 3D lines.