An underpants-shaped absorbent article having a longitudinal direction, a width direction, and a thickness direction that intersect each other in an unfolded state, the underpants-shaped absorbent article comprising: a front waist portion; a back waist portion; an absorbent main body that includes an absorbent body, a first joining portion in which a non-skin-side surface of an end portion of the absorbent main body on one side in the longitudinal direction is joined to the front waist portion using an adhesive; and a second joining portion in which a non-skin-side surface of an end portion of the absorbent main body on another side in the longitudinal direction is joined to the back waist portion using an adhesive, the absorbent main body being folded one time at a central position in the longitudinal direction, widthwise end portions of the front waist portion and widthwise end portions of the back waist portion being joined in a pair of waist joining portions, the absorbent body including a low-basis-weight portion in at least a central portion in the longitudinal direction, the low-basis-weight portion extending along the longitudinal direction, the low-basis-weight portion having a smaller basis weight than a surrounding area, a high-stiffness portion being provided in at least one of a longitudinal region extending from an inward end of the first joining portion to an outward end of the low-basis-weight portion and a longitudinal region extending from an inward end of the second joining portion to another outward end of the low-basis-weight portion, the high-stiffness portion being a portion that has a higher stiffness than the central position. a front waist portion; a back waist portion; an absorbent main body that includes an absorbent body, a first joining portion in which a non-skin-side surface of an end portion of the absorbent main body on one side in the longitudinal direction is joined to the front waist portion using an adhesive; and a second joining portion in which a non-skin-side surface of an end portion of the absorbent main body on another side in the longitudinal direction is joined to the back waist portion using an adhesive, the absorbent main body being folded one time at a central position in the longitudinal direction, widthwise end portions of the front waist portion and widthwise end portions of the back waist portion being joined in a pair of waist joining portions, the absorbent body including a low-basis-weight portion in at least a central portion in the longitudinal direction, the low-basis-weight portion extending along the longitudinal direction, the low-basis-weight portion having a smaller basis weight than a surrounding area, a high-stiffness portion being provided in at least one of a longitudinal region extending from an inward end of the first joining portion to an outward end of the low-basis-weight portion and a longitudinal region extending from an inward end of the second joining portion to another outward end of the low-basis-weight portion, the high-stiffness portion being a portion that has a higher stiffness than the central position. the absorbent main body being folded one time at a central position in the longitudinal direction, widthwise end portions of the front waist portion and widthwise end portions of the back waist portion being joined in a pair of waist joining portions, the absorbent body including a low-basis-weight portion in at least a central portion in the longitudinal direction, the low-basis-weight portion extending along the longitudinal direction, the low-basis-weight portion having a smaller basis weight than a surrounding area, the low-basis-weight portion extending along the longitudinal direction, the low-basis-weight portion having a smaller basis weight than a surrounding area, a high-stiffness portion being provided in at least one of a longitudinal region extending from an inward end of the first joining portion to an outward end of the low-basis-weight portion and a longitudinal region extending from an inward end of the second joining portion to another outward end of the low-basis-weight portion, the high-stiffness portion being a portion that has a higher stiffness than the central position. a longitudinal region extending from an inward end of the first joining portion to an outward end of the low-basis-weight portion and a longitudinal region extending from an inward end of the second joining portion to another outward end of the low-basis-weight portion, the high-stiffness portion being a portion that has a higher stiffness than the central position.