An absorbent article according to the present invention includes: a water-decomposable top sheet, a water-decomposable back sheet and a water-decomposable absorber placed between the top sheet and the back sheet. The back sheet is formed of multiple sheet pieces each being smaller than a main body of the absorbent article, and each sheet piece at least partially overlapping adjacent one or more of the other sheet pieces. In addition, an adhesive is applied to each overlapping region where adjacent two of the sheet pieces overlap each other.
