To easily and rapidly correct the deformation without interference with a bicycle body, a stay, or the like by providing a curved or bent outer pressing part on a tip of one substantially boomerang-shaped handle part, providing a projecting part on an inner side of a substantially S-shaped inner pressing part provided on a tip of the other handle part, and fitting the other handle part to the boomerang-shaped handle part in an expandable manner.

A tool is inserted diagonally from a lower part of a fender 3, and a handle part 1a and a boomerang-shaped handle part 1b are operated so that a projecting part 6 of an inner pressing part 2a is located at a deformed part 9. The projecting part 6 is tightly held by an outer pressing part 2b and the projecting part 6 while uniformly moving the projecting part 6 over the whole deformed part 9, and the deformed part 9 is gradually corrected to the original shape. The shape and dimensions of the projecting part 6 are changed according to the size and the location of the deformed part 9. In the case of correcting the deformed part 9 of the square fender 3, the outer pressing part 2b is preferably replaced by a straight bent one, and the projecting part 6 is replaced by a flat one.