This unfolding-type disposable diaper (1) has a longitudinal direction, a lateral direction, and a thickness direction that are orthogonal to each other, and has a first waist section (1a), a crotch section (1m), and a second waist section (1b) in a row in the longitudinal direction. Fastening tape (11, 11) fixed to each lateral end (1bsf, 1bsf) of the second waist section (1b) is engaged with the first waist section (1a), whereby a waist opening (1HB) and a pair of leg openings (1HL, 1HL) are formed. Cut-out lines (1c, 1c), which are for cutting out the parts (1bk, 1bk) of the second waist section (1b) to which the fastening tape (11, 11) is fixed, are formed in the unfolded diaper (1).本發明之展開型用後即棄式紙尿布,具有互相正交的縱方向、橫方向和厚度方向,並且具有並排在前述縱方向的第1腹圍部、胯下部和第2腹圍部,且藉由將分別固定在前述第2腹圍部的前述橫方向的各端部之各黏扣帶分別卡止於前述第1腹圍部,而形成一個腹圍開口部和一對腿圍開口部。在前述第2腹圍部當中用以切割固定住前述黏扣帶的部分之切割線,係於前述紙尿布的展開狀態下形成。1a‧‧‧第1腹圍部1am‧‧‧部分1asf(1sf)‧‧‧第1側翼片1asfe‧‧‧外端緣1at‧‧‧目標區域1b‧‧‧第2腹圍部1bk‧‧‧黏扣帶固定部1bsf(1sf)‧‧‧第2側翼片(端部)1bsfe‧‧‧外端緣1bsfe2‧‧‧外端部1c‧‧‧切割線1ca‧‧‧切斷線1m‧‧‧胯下部1msf(1sf)‧‧‧胯下部側翼片2‧‧‧頂部薄片2e‧‧‧端部4‧‧‧防漏薄片5‧‧‧外裝薄片6‧‧‧立體褶邊薄片(立體褶邊形成部)6g‧‧‧立體褶邊6j‧‧‧固定部6k‧‧‧基端部6r‧‧‧立體褶邊用彈性構件6s‧‧‧豎起部6sea‧‧‧端部6seb‧‧‧端部11‧‧‧黏扣帶11a‧‧‧帶基材11ap‧‧‧突出部分(抓持部)11m‧‧‧公材21‧‧‧腿圍彈性構件L1‧‧‧製品長度
