This invention relates to a disposable wearing article adapted to absorb and to hold excretion discharged thereon. 
Japanese Utility Model Application Publication No.  1994-9620A describes an open-type disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets wherein a pair of flaps extending outward from transversely opposite side edges of the core are formed with a plurality of slits extending in a longitudinal direction.  These slits are formed in the flaps extending in front and rear waist regions so that they are spaced one from another by a predetermined dimension in the longitudinal direction and spaced one from another by a predetermined dimension in a waist-surrounding direction.  The slits are widened in the waist-surrounding direction as the flaps are pulled in the waist-surrounding direction and thereupon a plurality of openings are defined in the flaps.  With this diaper of prior art put on a wearer""s body, dampness generated within the diaper can be relieved out through the openings and thereby undesirable stuffiness can be avoided. 
However, the diaper disclosed in the Publication is not formed with the slits in the vicinity of longitudinally opposite end portions of the diaper in the front and rear waist regions.  Consequently, it is impossible for the diaper to avoid stuffiness possibly occurring in the longitudinally opposite end portions tightly placed against the wearer""s skin.  In addition, the flaps extending outward from the front waist region are placed upon the respective flaps extending outward from the rear waist region and the openings may often be closed by the flaps placed one upon another in this manner.  In other words, it is apprehended that the openings do not function as vent holes. 
It is an object of this invention to provide a disposable diaper designed so that the openings defined as the diaper is put on the wearer""s body may be kept open and thereby stuffiness possibly occurring particularly in the vicinity of the longitudinally opposite end portions of the diaper. 
According to this invention, there is provided a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these sheets so as to define a front waist region, a rear waist region and a crotch region extending between these waist regions, and an elastic member which is stretchable in a waist-surrounding direction being bonded under tension to at least one of longitudinally opposite end portions of the diaper in the front and rear waist regions. 
According to this invention the elastic member associated with the waist-opening has transversely opposite ends extending in the longitudinal direction and upper and lower edges extending in the waist-surrounding direction, and a plurality of slits extending through the diaper in a thickness direction thereof and extending in the longitudinal direction are arranged to be spaced one from another by a predetermined dimension in the waist-surrounding direction between the transversely opposite ends of the elastic member associated with the waist-opening and spaced one from another by a predetermined dimension in the longitudinal direction between the vicinity of the upper edge and the vicinity of the lower edge of the elastic member associated with the waist-opening. 
According to one embodiment of this invention, the slits are formed in the middle zone of the elastic member associated with the waist-opening as viewed in the waist-surrounding direction. 
According to another embodiment of this invention, each of the slits is dimensioned in the longitudinal direction so as to be progressively reduced from the array of the slits defined in the vicinity of the upper edge to the array of the slits defined in the vicinity of the lower edge of the elastic member associated with the waist-opening.