The present invention provides an absorbent article. Before use and during use, this absorbent article can maintain the same physical properties as a conventional absorbent article using a constituentmember consisting of a synthetic resin. When discarded and buried after use, the absorbent article breaks down within a short period of time, and thus the environmental burden on a landfill can be reduced. This absorbent article is formed by a synthetic resin sheet in which at least one among a surface sheet (2) and a reverse-surface sheet (3) includes, at a specific mass ratio, an oxidative decomposition agent consisting of a mixture of a carboxylate and a rare earth compound. In addition, the absorbent article includes, at a specific mass ratio, an oxidative decomposition promotor consisting of a peroxide on at least one among a surface side, which is not closer to the skin than an absorbing body (4), and the inside of water-sensitive capsules (CP) included in the absorbing body (4).