Disclosed is a disposable diaper in boxer short form which enables easy alteration of the length of leg-circumference tube sections. The disposable diaper in boxer short form (1) is provided with a front body sheet (11), which covers abdomen of the wearer a back body sheet (12), which covers the back of the wearer and a pair of leg-circumference tube sections (17), which have leg-circumference openings (LO), and which are installed on both sides of the location of the crotch and cover the circumference of the legs of the wearer. The front body sheet (11) and back body sheet (12) form a waist opening (WO), being joined to each other at seams (21) on both sides and a seam (22) located at the crotch. The leg-circumference tube sections (17) are partitioned into a plurality of ring-shaped sections (17A) which can be separated from each other by means of perforations (27, etc.) running in the circumferential direction thereof.
