An absorbent article having an up-down direction and comprising: an absorbent main body that has a longitudinal direction, a width direction, and a thickness direction that intersect each other; a stomach-side member arranged at an end portion on one side of the absorbent main body; and a back-side member arranged at an end portion on another side of the absorbent main body, wherein the absorbent main body has a pair of leak-proof walls in respective side end portions, the pair of leak-proof walls each have a skin-side portion that includes a plurality of elastic members and a non-skin-side portion that is arranged on a non-skin side of the skin-side portion, the pair of leak-proof walls each have a joining portion in which at least portions of mutually opposing surfaces of the skin-side portion and the non-skin-side portion are joined, and a non-joining portion that is provided above the joining portion in the up-down direction, the mutually opposing surfaces not being joined in the non-joining portion, the joining portions are provided inward, with respect to the width direction, of leading ends of the leak-proof walls, and each of the joining portions is at least partially overlapped with the stomach-side member or the back-side member in the up-down direction, and wherein a stomach-side adhesion region, in which the absorbent main body and the stomach-side member are adhered together, is provided in the end portion on the one side of the absorbent main body, a back-side adhesion region, in which the absorbent main body and the back-side member are adhered together, is provided in the end portion on the other side of the absorbent main body, and a lower end of the stomach-side member is located below the stomach-side adhesion region, or a lower end of the back-side member is located below the back-side adhesion region. an absorbent main body that has a longitudinal direction, a width direction, and a thickness direction that intersect each other; a stomach-side member arranged at an end portion on one side of the absorbent main body; and a back-side member arranged at an end portion on another side of the absorbent main body, wherein the absorbent main body has a pair of leak-proof walls in respective side end portions, the pair of leak-proof walls each have a skin-side portion that includes a plurality of elastic members and a non-skin-side portion that is arranged on a non-skin side of the skin-side portion, the pair of leak-proof walls each have a joining portion in which at least portions of mutually opposing surfaces of the skin-side portion and the non-skin-side portion are joined, and a non-joining portion that is provided above the joining portion in the up-down direction, the mutually opposing surfaces not being joined in the non-joining portion, the joining portions are provided inward, with respect to the width direction, of leading ends of the leak-proof walls, and each of the joining portions is at least partially overlapped with the stomach-side member or the back-side member in the up-down direction, and wherein a stomach-side adhesion region, in which the absorbent main body and the stomach-side member are adhered together, is provided in the end portion on the one side of the absorbent main body, a back-side adhesion region, in which the absorbent main body and the back-side member are adhered together, is provided in the end portion on the other side of the absorbent main body, and a lower end of the stomach-side member is located below the stomach-side adhesion region, or a lower end of the back-side member is located below the back-side adhesion region.