PURPOSE: To obtain a channel bar excellent in butt weldability and appearance by orderly applying rough rolling process by which an intermediate product is formed, finishing process by which a channel bar is formed to a base stock.

CONSTITUTION: Caliber rolling is applied to the base stock 1 which is heated at a prescribed temp. with plural pairs of 2-high rolling roll which are arranged in parallel each other, of which at least one of them is revolved with a driving device and on which prescribed calibers are formed. A pair of flange parts 3 are outwardly inclined to each perpendicular, the web part 4 is made into a projecting shape that the web part is protruded on the side of the flange part 3 and that its middle part 4a is flat, both end parts of the web part 4 are joined at approximately right angles to the flange parts 3, the intermediate product of which the thickness of the flange parts 3 and web part 4 are approximately same as the product is formed. And also the intermediate product is rolled in the thickness direction after convex parts 3f and concave part 3g are formed in the tip part 8 of each flange part 3 and rough rolling process by which the flatness at the tip of the flange parts 3 is raised and finishing process by which the channel bar with the flange parts vertical to the web part 4 is formed with plural pairs of forming rolls are orderly executed.