The present invention aims to provide a disposable pants-type diaper improved so that the separator being well known per se may fulfill its primary function. A disposable pants-type diaper (1) includes an innermost sheet (20) lying between a liquid-pervious inner sheet (2) covering a bodily fluid-absorbent core and diaper wearers skin and attached to the inner sheet (2) to form a body waste retaining space (31). The innermost sheet (20) is formed with a front opening (33) allowing the passage of urine into the body waste retaining space (31) and a rear opening (34) allowing the passage of feces into the body waste retaining space (31). A portion of the innermost sheet (20) extending between the front opening (33) and the rear opening (34) droops down and a lower end (35) thereof to form a separator (20a). The separator is provided with a sheet member (81) having a thickness (N) in a range of 1 to 10mm, a width in a range of 10 to 70mm and a height (L) in a range of 30 to 100% of a dimension (K) of the separator (20a) in the vertical direction and functioning to restrict a degree of deformation potentially occurring in the separator.
