An absorbent article having a longitudinal direction and a transverse direction orthogonal to the longitudinal direction includes an absorbent panel having a ventral region, a dorsal region and an intermediate region between the ventral and dorsal regions in the longitudinal direction. The absorbent panel includes a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid absorbent core lying between the liquid-permeable topsheet and the liquid-impermeable backsheet. The absorbent core is arranged in a limited area extending from a zone of the intermediate region defined adjacent to a slit for formation of an opening into which the pet animals tail is inserted into the ventral region and has a first end lying in the ventral region and a second end lying in the intermediate region. A dimension of the ventral region in the transverse direction gradually narrows from the side of the second end toward the first end.
