The present invention relates to a disposable diaper. In a disposable diaper comprising a pair of side flaps respectively extending from an end portion in a lateral direction of the diaper main body and a fixing tape disposed in proximity of a farthest edge of the respective side flaps, the fixing tape is provided with a hook member, the fixing tape and the side flaps are to be engaged via the hook member, and an engaging region on the side flaps where the fixing tape is to be engaged includes portions having a different engaging force with the hook member. As a result, the fixing tape can be temporarily fixed with a modest engaging force, despite the hook member having a greater engaging force.