The present invention addresses the problem of, in an absorbent article, preventing the leakage of fiber constituting an absorbent core from a non-covered region through a liquid-permeable layer, said leakage possibly occurring when the strength of the absorbent core is decreased due to liquid absorption. To solve this problem, provided is a sanitary napkin (1) which comprises a top sheet (2), a back sheet (3) and an absorbent core (4) that is interposed between the top sheet (2) and the back sheet (3), wherein: the absorbent core (4), which involves a non-covered region where the constituting fiber is exposed on the surface and in contact directly with the top sheet (2), contains a thermoplastic resin fiber, said thermoplastic resin fiber containing as a monomer component an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof, at a mixing ratio by mass to a cellulose-based water absorbent fiber of 1/9 or more and the wet fiber fall-off rate of the absorbent core (4) is controlled to 13.3% or less.
