An absorbent article having a lengthwise direction, a widthwise direction and a thickness direction, and comprising an absorbent body, and a pair of side flaps which extend outward from both ends in the widthwise direction of the absorbent body, on a dorsal side in the lengthwise direction of the absorbent body, wherein each of the pair of side flaps comprises: a stretching member which is in the form of a sheet and stretchable in the widthwise direction, and sheet members (7a, 7b) which are respectively layered on both sides in the thickness direction of the stretching member, and has: a stretching member placement section (Ea) where the stretching member and the sheet members (7a, 7b) overlap in the thickness direction, and extending sections (Pa, Pb) where the sheet members (7a, 7b) are extended respectively on an outer side and an inner side in the lengthwise direction of the stretching member placement section (Ea), wherein the sheet members (7a, 7b) are formed of nonwoven fabrics, at least a sheet member on a skin side, of the sheet members layered on both sides in the thickness direction of the stretching member, is a nonwoven fabric having a concavo-convex structure, the nonwoven fabric with the concavo-convex structure includes: a plurality of raised sections extending in the lengthwise direction and aligned at prescribed intervals in the widthwise direction, and a plurality of recess sections situated between mutually adjacent raised sections, and when the side flaps are in a state of their natural length, the extending sections (Pa, Pb) have multiple wrinkles aligned in the widthwise direction, running along the lengthwise direction. a stretching member which is in the form of a sheet and stretchable in the widthwise direction, and sheet members (7a, 7b) which are respectively layered on both sides in the thickness direction of the stretching member, and has: a stretching member placement section (Ea) where the stretching member and the sheet members (7a, 7b) overlap in the thickness direction, and extending sections (Pa, Pb) where the sheet members (7a, 7b) are extended respectively on an outer side and an inner side in the lengthwise direction of the stretching member placement section (Ea), wherein the sheet members (7a, 7b) are formed of nonwoven fabrics, at least a sheet member on a skin side, of the sheet members layered on both sides in the thickness direction of the stretching member, is a nonwoven fabric having a concavo-convex structure, the nonwoven fabric with the concavo-convex structure includes: a plurality of raised sections extending in the lengthwise direction and aligned at prescribed intervals in the widthwise direction, and a plurality of recess sections situated between mutually adjacent raised sections, and when the side flaps are in a state of their natural length, the extending sections (Pa, Pb) have multiple wrinkles aligned in the widthwise direction, running along the lengthwise direction. a stretching member placement section (Ea) where the stretching member and the sheet members (7a, 7b) overlap in the thickness direction, and extending sections (Pa, Pb) where the sheet members (7a, 7b) are extended respectively on an outer side and an inner side in the lengthwise direction of the stretching member placement section (Ea), wherein the sheet members (7a, 7b) are formed of nonwoven fabrics, at least a sheet member on a skin side, of the sheet members layered on both sides in the thickness direction of the stretching member, is a nonwoven fabric having a concavo-convex structure, the nonwoven fabric with the concavo-convex structure includes: a plurality of raised sections extending in the lengthwise direction and aligned at prescribed intervals in the widthwise direction, and a plurality of recess sections situated between mutually adjacent raised sections, and when the side flaps are in a state of their natural length, the extending sections (Pa, Pb) have multiple wrinkles aligned in the widthwise direction, running along the lengthwise direction. a plurality of raised sections extending in the lengthwise direction and aligned at prescribed intervals in the widthwise direction, and a plurality of recess sections situated between mutually adjacent raised sections, and when the side flaps are in a state of their natural length, the extending sections (Pa, Pb) have multiple wrinkles aligned in the widthwise direction, running along the lengthwise direction.