To prevent double folds and eliminate slacks on trousers and prevent small creases, by joining a pair of forming bodies so that the length between the ends can be extended or contracted and setting the forming bodies at the inside of the foot of trousers so as to be oppositely arranged and extend or contract the foot from the inside.

The outside shape of a pair of forming bodies 1a, 1b are formed to be nearly symmetrical with a thin stainless steel plate or the like for instance and thin parts 2 are formed at the ends thereof. When trousers B are pressed by the forming tool for trouser press, fingers are inserted at first into manipulation parts 5a, 5b and toe length between the ends of the forming bodies 1a, 1b is made short against the urging force of an urging body 6 and the forming tool is inserted in inside of the foot of trousers. And the thin parts 2 of the ends of the forming bodies 1a, 1b are oppositely arranged against the folds of the trousers and the force acting on the manipulation part 5a, 5b is decreased. Then, the shaft 4 slides parallelly in the groove 3 by the urging force of the urging body 6 and the foots of the trousers B can be extended from the inside by oppositely arranging the forming tool to the folds of the trousers B.