The present invention aims to improve a leak-barrier effect of the disposable pants-type diaper provided with a separator serving to prevent urine and feces from being mixed with each other. A disposable pants-type diaper has the innermost sheet member (21) interposed between a liquid-pervious inner sheet (23) covering a bodily fluid-absorbent structure (22) and the diapers skin. The innermost sheet member (21) is formed with a front opening (31) and a rear opening (32) communicating with a body waste retaining space (25) defined between the inner sheet (23) and the innermost sheet member (21). A portion of the innermost sheet member (21) extending between these two openings (31, 32) is folded and joined together in a pair of joints arranged on a vertical center line (P-P) of the diaper and extends downward toward the inner sheet (23) to form a separator. The innermost sheet member (21) is provided between a top (31t) of the front opening (31) and the associated one of the joints on the center line (P-P) and between a top (32t) of the rear opening (32) and associated one of the joints on the center line (P-P) with elastic regions (71, 72), respectively, adapted to be contractible in a transverse direction (B), on one hand, and with a non-elastic region (73) between the elastic regions (71, 72), on the other hand.
