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).
