Provided is a soft box having a plurality of poles, an adapter ring having a plurality of holes into which the plurality of poles is correspondingly coupledly inserted, and a reflecting cloth adapted to connect the plurality of poles in such a manner as to reflect light therefrom, the soft box including: a zipper mounted on the reflecting cloth between the neighboring poles; and an auxiliary reflecting cloth disposed on the reflecting cloth adjacent to the inner side of the zipper along the longitudinal direction of the zipper in such a manner as to cover the inner surface of the zipper.