A disposable diaper comprising: a fastening tape having a tab part which is formed at one end of a tape substrate, a fixing part which is formed at the other end of the tape substrate, and an adjustment part which is formed between the tab part and the fixing part a diaper main body having a front part, a back part and a crotch part positioned between the front part and the back part wherein an attachment is fixed to the tab part, the fastening tape is attached to a side end of the front or back part of the diaper main body at the fixing part, the adjustment part is folded and temporarily joined to the diaper main body and/or the fastening tape at a joining part, and a length of the fastening tape between the attachment and the joining part which is the nearest to the attachment is longer than a length between an outer edge of the diaper main body and the joining part which is the nearest to the attachment. According to the disposable diaper of the present invention, the length of the fastening tape is adjustable in accordance with a size of a wearers waist, and hence the disposable diaper of one size can be worn by people of various body types.
