The problem to be solved by the present invention is to provide an absorbent article in which a reduction in liquid absorbency caused by the hydrophobicity of thermoplastic resin fiber is prevented through the use of thermoplastic resin fiber that includes unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, or a mixture of these as a monomer component. The present invention solves this problem by providing a sanitary napkin provided with a top sheet, a back sheet, and an absorbent body disposed between the top sheet and the back sheet. The absorbent body has an absorbent material layer that contains a cellulose-based hydrophilic fiber and a thermoplastic resin fiber that includes unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, or a mixture of these as a monomer component in a mass ratio of 90:10 to 50:50. The top sheet has an integrated section that is heat-treated together with the absorbent material layer so as to be integrated with the absorbent material layer.