An open-type disposable diaper having a longitudinal direction, a transverse direction and a thickness direction perpendicular to one another includes: a first waist part (1a) a crotch part (1m) a second waist part (lb), the first waist part, the crotch part and the second waist part being arranged in this order in the longitudinal direction fastening tapes (11) which are respectively fixed to the transverse ends of the second waist part, and which are fastened to the first waist part and thereby a waist opening (1HB) and a pair of leg openings (1HL) are formed and a tear-off line (1c) that is for cutting out a section of the second waist part to which the fastening tape is fixed and that is formed in a state in which the diaper is spread out.
