The invention relates to an absorbent article (1) comprising an upper, liquid-permeable cover sheet (2), a lower, liquid-impermeable cover sheet (3), and an absorption body (4) arranged between the cover sheets (2, 3), said article (1) defining a longitudinal direction, a front portion (5) in the longitudinal direction, a rear portion (7), and a middle portion (6) arranged between said portions (5, 7), said article (1) additionally comprising first and second side barriers (8, 9) along the respective longitudinal side, and each side barrier (8, 9) in turn comprising at least one longitudinal elastic element (10, 11; 14, 15), said first and second side barriers (8, 9), viewed from above, defining a shape which narrows in the direction towards said front portion (5) so that the distance, in the transverse direction of the article (1), between said elastic elements (10, 11, 14, 15) is greater in said rear portion (7) than in said front portion (5). According to the invention, each side barrier (8, 9) is arranged such that, when it is secured in contact with said front portion (5), it defines a folded structure of substantially Z-shaped cross section with a fold (22, 23) directed towards the inside of said article (1). The invention affords an improved absorbent article, principally in the form of a diaper for very small infants, which effectively prevents leakage of loose, running excrement and which provides a good fit and is easy to place on a user.