A water-decomposable absorbent article including an absorbent body that has a water-decomposable top sheet, a water-decomposable back sheet, a water-decomposable adsorbent core sandwiched between the top sheet and the back sheet, and an adhesive layer provided on the back sheet to fit the absorbent article to an external support; and a water-decomposable release sheet for protecting the adhesive layer before use with covering the adhesive layer. The release sheet includes a release layer that faces the adhesive layer, a water-decomposable fibrous layer, and a water-soluble polymer layer sandwiched between the release layer and the fibrous layer. A basis weight of the release layer is at least 0.05 g/m.sup.2 but smaller than 0.3 g/m.sup.2, and an equilibrium contact angle between a surface of the release layer and a water drop thereon is at least 100 degrees.