On the back sheet 120 side, back-side recessed portions 135 recessed toward the top sheet 110 are provided in a surface of the absorber 130 of the disposable diaper 1. The back-side recessed portions 135 include multiple grooves 135a, 135b which are continuous in the longitudinal direction L of the absorber 130. The back-side recessed portions 135 is visible from an outside of the back sheet 120 in a state before the disposable diaper 1 is used, and when the absorber absorbs liquid, the depth D of the back-side recessed portions 135 is made smaller than that before the absorber absorbs liquid. When the hydrophilic fiber and the particulate SAP swells, and thereby the absorber 130 expands in at least the thickness direction thereof, the back-side recessed portions 135 seems to disappear from the outside.
