PROBLEM TO BE SOLVED: To provide a disposable diaper allowing a user to adjust fitness of the leg peripheries.SOLUTION: The disposable diaper includes: a liquid permeable top sheet forming a body-side surface a liquid impermeable sheet 11 located in a back side thereof an absorber 56 disposed between the liquid permeable top sheet and the liquid impermeable sheet 11 and side flap parts SF extending in width-directional both sides of the absorber 56. The disposable diaper further includes gather materials 80 for tightening the leg peripheries in the side flap parts SF.