The present invention relates to disposable diapers having a means adapted for receiving feces. 
There has already been proposed disposable diapers having a pocket as a means adapted for receiving feces, comprising a first sheet facing a wearer's skin and a second sheet facing the wearer's garment wherein, in a crotch region of the diaper, the first sheet is formed with a through-hole communicating with the feces receiving pocket defined between the first and second sheets so that the through-hole may be aligned with anus of the wearer when the diaper is put on the wearer's body. 
For example, U.S. Pat.  No.  4,990,147 (Citation 1) discloses a disposable diaper comprising a liquid-impervious backsheet, a liquid-pervious liner and a bodily waste absorbent core interposed between the backsheet and the liner.  The liner is formed with a through-hole adapted to guide feces therethrough toward the core and thereby to protect the wearer's skin from being contaminated with feces.  The liner is formed at least partially by an elastic panel serving to keep a periphery of the through-hole in close contact with an area surrounding the anus.  In this diaper, a stock material for the elastic panel may be selected from the group consisting of a nonwoven fabric of a polyurethane elastic threads and a knitted fabric of inelastic threads. 
WO 03/009795 A1 (Citation 2) discloses a disposable diaper as illustrated in FIGS.  8 and 9 of the accompanying drawings wherein FIG.  8 illustrates the diaper in its elastically stretched state and FIG.  9 illustrates the diaper in its elastically contracted state.  The known disposable diaper comprises a backsheet 126 and a topsheet 124 formed with a slit-type opening 130 allowing feces to pass therethrough so that a pocket serving for receiving feces may be defined between the top- and backsheets 124, 126.  Along a pair of transversely opposite side edges of the slit-type opening 130, elastic bands are bonded in stretched states to the topsheet 124 so as to form elastic areas 131, 132 extending in parallel with the center line X in a longitudinal direction.  The elastic area 131 is contiguous to an elastic area 143 obliquely extending toward a front waist region so as to draw apart gradually from the center line X, on one hand, and to an elastic area 145 obliquely extending toward a rear waist region so as to draw apart from the center line X, on the other hand.  In the similar manner, the elastic area 132 is contiguous to an elastic area 144 obliquely extending toward the front waist region so as to draw apart gradually from the center line X, on one hand, and to an elastic area 146 obliquely extending toward a rear waist region so as to draw apart gradually from the center line X, on the other hand.  The elastic areas 131, 143, 145 cooperate with the elastic areas 132, 144, 146 opposed to the areas 131, 143, 145 to define a generally X-shaped elastic zone.  The slit-type opening 130 may be positioned in alignment with the anus when the known diaper is put on the wearer's body. 
The liner of the diaper disclosed in Citation 1 as well as the topsheet of the diaper disclosed in Citation 2 may be formed from the elastic sheet.  One example of such elastic sheet is a nonwoven fabric of elastic threads such as polyurethane elastic threads, which falls, however, into disfavor with wearer's mothers due to uncomfortable rubber-like touch peculiar to this nonwoven fabric.  The other example of such elastic sheet is knitted fabric of inelastic threads, which is, however, too costly to be used for the disposable diaper.  For the diaper disclosed in Citation 2, the elastic threads may be attached to the nonwoven fabric of inelastic threads to ensure that this nonwoven fabric is partially elasticized.  The topsheet formed from a nonwoven fabric made of inelastic threads and partially elasticized in this manner certainly solves the problem that the wearer might experience uncomfortable rubber-like touch so far as the diaper is in the state as shown in FIG.  8.  However, in response to elastic contract of the elastic bands, a width W of the slit-type opening is varied and simultaneously the crotch region is formed with a plurality of irregular and outstanding corrugations 150.  Variation occurring in the width W of the slit-type opening makes it difficult to position the side edges of the slit-type opening in alignment with the both lateral sides of the wearer's anus.  Such instable width of the opening must be alleviated by minimizing the width W of the opening and covering the wearer's skin with the topsheet in the vicinity of the diaper wearer's anus so that the wearer's skin may be protected from being contaminated over a wide range.  Formation of a plurality of corrugations prevents the topsheet from being kept in close contact with the wearer's skin, resulting in that bodily waste may leak out beyond the periphery of the slit-type opening and/or appearance of the diaper put on the wearer's body may be damaged.  It is a principal object of the present invention to improve the disposable diaper of prior art so that the problems as have been described just above may be reliably solved.