A post-heating treatment device performs a post-heating treatment for a welded section of a rail, after an induction heating coil is automatically disposed at a predetermined position based on the welded section. The device includes welded section detecting unit for detecting the position of a welded section on a rail, a first coil and a second coil that form an induction heating coil, first coil moving unit for moving the first coil to a position spaced apart from the rail at a predetermined distance, second coil moving unit for moving the second coil to a position separated from the rail at a predetermined distance, where the second coil is contacted to the first coil, clamping unit for pressing against the contact portion between the first coil and the second coil, and current applying unit for applying a predetermined current to the formed induction heating coil.