An absorbent article having a longitudinal direction, a transverse direction and a thickness direction that are mutually perpendicular, and comprising an abdomen side section and a dorsal side section, both edges of the abdomen side section and dorsal side section in the transverse direction overlapping in the thickness direction along the longitudinal direction and being joined together by a pair of joint sections (14a, 14b), wherein each of the pair of joint sections (14a, 14b) comprises a plurality of fused sections situated along the longitudinal direction, each of the plurality of fused sections includes: a core section where a sheet member of the abdomen side section and a sheet member of the dorsal side section are fused together in the thickness direction, and a perimeter wall section where the sheet member of the abdomen side section and the sheet member of the dorsal side section are fused together in the thickness direction, so as to surround the core section in a tubular manner in the thickness direction, and when a direction in which a difference in widths between the perimeter wall section located on both outer sides of the core section is smaller is defined as a first direction and a direction in which the difference is larger is defined as a second direction, among the longitudinal direction and the transverse direction, in the second direction, a first dimension which is a width of the perimeter wall section located on a second direction first side that is one side of the core section in the second direction, is equal to or more than 40% and less than 100% of a second dimension which is a width of the perimeter wall section located on a second direction second side that is the other side of the core section in the second direction, wherein in the first direction, widths of the perimeter wall section located on both outer sides of the core section both increase from the second direction first side toward the second direction second side. each of the pair of joint sections (14a, 14b) comprises a plurality of fused sections situated along the longitudinal direction, each of the plurality of fused sections includes: a core section where a sheet member of the abdomen side section and a sheet member of the dorsal side section are fused together in the thickness direction, and a perimeter wall section where the sheet member of the abdomen side section and the sheet member of the dorsal side section are fused together in the thickness direction, so as to surround the core section in a tubular manner in the thickness direction, and when a direction in which a difference in widths between the perimeter wall section located on both outer sides of the core section is smaller is defined as a first direction and a direction in which the difference is larger is defined as a second direction, among the longitudinal direction and the transverse direction, in the second direction, a first dimension which is a width of the perimeter wall section located on a second direction first side that is one side of the core section in the second direction, is equal to or more than 40% and less than 100% of a second dimension which is a width of the perimeter wall section located on a second direction second side that is the other side of the core section in the second direction, wherein in the first direction, widths of the perimeter wall section located on both outer sides of the core section both increase from the second direction first side toward the second direction second side. a core section where a sheet member of the abdomen side section and a sheet member of the dorsal side section are fused together in the thickness direction, and a perimeter wall section where the sheet member of the abdomen side section and the sheet member of the dorsal side section are fused together in the thickness direction, so as to surround the core section in a tubular manner in the thickness direction, and when a direction in which a difference in widths between the perimeter wall section located on both outer sides of the core section is smaller is defined as a first direction and a direction in which the difference is larger is defined as a second direction, among the longitudinal direction and the transverse direction, in the second direction, a first dimension which is a width of the perimeter wall section located on a second direction first side that is one side of the core section in the second direction, is equal to or more than 40% and less than 100% of a second dimension which is a width of the perimeter wall section located on a second direction second side that is the other side of the core section in the second direction, wherein in the first direction, widths of the perimeter wall section located on both outer sides of the core section both increase from the second direction first side toward the second direction second side.