Disposable absorbent incontinence diaper (2) of the open type, with a main part (4), comprising a front area (6) with front side longitudinal edges (42), a rear area (8) with rear side longitudinal edges (41 ) and a crotch zone (10) that is located between said two zones in the longitudinal direction (28) and is placed between the user's legs, the main part (4) comprising an absorbent body (12), and with rear side sections (20) added to both sides of the rear area (8) and front side sections (22) added to both sides of the front area (6), which extend in the transverse direction (30) to beyond the front and rear side longitudinal edges (42, 41) of the main part (4), and where the rear side sections (20) have first closing means (32) close to the leg openings with supports of closing and in gift of the closing means (32) can be detachably immobilized at least on the outer side of the front side sections (22) and the front area (6) and the rear area (8) can thus be connected to each other, in where, to form rear areas (51) of the leg sectional opening of the lateral section, a lower edge (64) of the rear lateral sections (20) is curved in shape, with the lower edge (64) of the rear lateral sections ( 20), with a length A and a width B, a convex section (44) with an end point P, characterized in that the ratio of the length A to the width B of the lower edge (64) of a rear side section (20 ) ascending to 0.40-0.90 and the ratio of the longitudinal extension E of the end point P to its transverse extension F amounts 0.15-0.80.Pañal de incontinencia absorbente desechable (2) del tipo abierto, con una parte principal (4), que comprende una zona delantera (6) con bordes longitudinales laterales delanteros (42), una zona trasera (8) con bordes longitudinales laterales traseros (41) y una zona de bragadura (10) que está situada entre dichas dos zonas en la dirección longitudinal (28) y viene a quedar situada entre las piernas del usuario, comprendiendo la parte principal (4)
