An absorbent article (1) having an up-down direction and includes: an absorbent main body (10); a stomach-side member (3) arranged to an end portion on one side of the absorbent main body (10) ; and a back-side member (4) arranged to an end portion on another side, wherein the absorbent main body (10) has a pair of leak-proof walls (50) in respective side end portions, the leak-proof walls (50) each have a skin-side portion (51) that includes a plurality of elastic members (55) and a non-skin-side portion (52), the pair of leak-proof walls each have a joining portion (61) in which at least portions of mutually opposing surfaces of the skin-side portion (51) and the non-skin-side portion (52) are joined, and a non-joining portion (62) that is provided above the joining portion (61), the mutually opposing surfaces not being joined in the non-joining portion (62), the joining portions (61) are provided inward, with respect to the width direction, of leading ends of the leak-proof walls (50), and each of the joining portions (61) is at least partially overlapped with the stomach-side member (3) or the back-side member (4) in the up-down direction.