Included are: an absorbent main body (10) including an absorbent core (11)； and leak-proof walls (50) in a pair that have elastic members (55) stretchable in a longitudinal direction and are provided on both sides in a lateral direction of the absorbent main body (10), the absorbent core (11) including a concave portion (11c) that is concave inward in the lateral direction in the central portion in the longitudinal direction, the leak-proof walls (50) each including a joining part (61) where portions of a surface of each of the leak-proof walls (50) are joined to each other on one side in a thickness direction, in at least a part of a region corresponding to the concave portion (11c) in the longitudinal direction , he leak-proof walls (50) each including a non-joining part (62) in at least one of a region on one end side and a region on the other end side in the longitudinal direction with respect to the joining part (61)), the non-joining part (62) being where portions of a surface of each of the leak-proof walls are not joined to each other on the one side in a thickness direction.
