To provide a side edge truing-up method and a side edge truing-up device capable of easily side edge truing-up of shape steel.

Each of three side edge truing-up members 27, 28 and 29 pivoted on a device frame 26 is independently tilted by hydraulic cylinders 30, 31 and 32. Side edge truing-up bodies 34, 36 and 37 are arranged on the side edge truing-up members 27, 28 and 29. A plurality of chevron sections 35 are formed on the side edge truing-up bodies 34, 36 and 37 along the width direction of a rail. A first side edge truing-up member 27 aligns the side edge of a rail by pushing up the rail from a transfer conveyer and tilting it. A second side edge truing-up member 28 aligns the side edge of the rail by pushing up the rail from the first side edge truing-up member 27. A third side edge truing-up member 29 aligns the side edge of the rail by pushing up the rail from the second side edge truing-up member 28. The third side edge truing-up member 29 moves downward to lay the side edge aligned rails on the placing surface of the transfer conveyer in the condition that the seats of the rails are stacked one above the other.