PROBLEM TO BE SOLVED: To provide an underpants type disposable diaper allowing surely tearing in the longitudinal direction a side seal part formed by bonding both side edge parts of an abdominal side and a back side of an exterior body.SOLUTION: An underpants type disposable diaper is formed with a waist opening part WO, a pair of leg openings LO and a side seal part 21 extending in a longitudinal direction YD by superposing both side edge parts of an abdominal side F and a back side B of an exterior body 20. A tearing start part 31 is provided in the side seal part 21, a plurality of first bonding bands 21A extending mainly in a width direction XD are intermittently provided in the longitudinal direction YD in the tearing start part 31 and between the waist opening part WO and the leg opening LO, respectively, and a plurality of second bonding bands 21B extending mainly in the longitudinal direction YD are intermittently provided in the longitudinal direction YD in the tearing start part 31 and inside the first bonding band 21A.SELECTED DRAWING: Figure 9【課題】外装体の腹側及び背側の両側縁部が接合されて形成されたサイドシール部を、縦方向に確実に引き裂くことができるパンツタイプ使い捨ておむつとする。【解決手段】外装体２０の腹側Ｆ及び背側Ｂの両側縁部が重ねられて、ウエスト開口部ＷＯ及び左右一対の脚開口部ＬＯ、並びに縦方向ＹＤに延在するサイドシール部２１が形成されたパンツタイプ使い捨ておむつについて、サイドシール部２１に引裂き開始部３１を設け、この引裂き開始部３１とウエスト開口部ＷＯ及び脚開口部ＬＯとの間にそれぞれ、主として幅方向ＸＤに延在する第一接合帯２１Ａを縦方向ＹＤに間欠的に複数条設け、引裂き開始部３１及び第一接合帯２１Ａの内方に、主として縦方向ＹＤに延在する第二接合帯２１Ｂを縦方向ＹＤに間欠的に複数条設ける。【選択図】図９
