A pet diaper (1) is provided with a belly-side
waist-surrounding section (2), a back-side
waist-surrounding section (3), a
crotch section (4), a pair of fastening tabs (50), and a
tail insertion section (70), a pair of leg opening sections (4lh) are provided on both sides of the
crotch section (4) in the left-right direction, and a through-section (40) that penetrates the
crotch section (4) in the thickness direction is provided on the belly side from the center position in the front-back direction. Among areas of a portion surrounded by a straight line connecting a dorsal end (2eb) of a lateral edge of the dorsal
waist-surrounding section (2) in the left-right direction and a dorsal end (3ef) of a lateral edge of the dorsal waist-surrounding section (3) in the left-right direction and a
peripheral edge of a leg opening section (41h), an area (A) on the
ventral side than a central position in the front-rear direction is larger than an area (B) on the backrest side than the central position in the front-rear direction.