A disposable diaper adapted to prevent the sheets from digging into the wearer's posterior rugae. A disposable diaper (10) has a longitudinal direction (Y), a transverse direction (X) and a longitudinal axis (P-P) extending in the longitudinal direction to bisect a dimension in the transverse direction (X), and including a chassis (14) having a skin-facing surface and a non-skin-facing surface, a front waist region (11), a rear waist region (12), a crotch region (13) lying between the front and rear waist regions (11, 12) and a liquid-absorbent structure (15) extending in the longitudinal direction (Y) at least in the crotch region (13) . The chassis includes a first sheet (22), a second sheet (23) and a pair of first leg elastics (26) and a pair of second leg elastics (27) both pairs being interposed between the first sheet and the second sheet so as to be symmetric about the longitudinal axis, a main portion (24) and a pair of lateral elastic regions (25) folded so as to face the main portion and attached to only front and rear ends in the longitudinal direction of the main portion. The first leg elastics and the second leg elastics are arranged in these lateral elastic regions (25) . The first leg elastics are arranged so as to be relatively close to the longitudinal axis as viewed in the transverse direction and to be rectilinear in the longitudinal direction. The second leg elastics are arranged at a distance from the longitudinal axis as viewed in the transverse direction larger than a distance from the longitudinal axis at which the first leg elastics are arranged and have rectilinear portions (29) extending in the longitudinal direct at least in a portion of the crotch region close to the front waist region and curved portions (30) spaced apart outwardly from each other from the rear waist region side ends of the rectilinear portions.
