PROBLEM TO BE SOLVED: To prevent leakage from circumferences of the legs by improving fitting property of flat gathers toward the circumference of the legs without deteriorating wearing feeling of a diaper and work efficiency of wearing the diaper.SOLUTION: In a disposable paper diaper 1 formed with flat gathers FG, outer portions X2 of sheets 20 are attached to both sides of back sheet 2 along the longitudinal direction on both sides of the outer surface side of the back sheet 2, and inner portions X1 are attached to both longitudinal end part on the back sheet 2 sides and are formed as free pieces 15 facing inward without being attached to the middle region of the back sheet 2 side in the longitudinal direction. Auxiliary gathers AG each having an elastic flexible member 21 along the longitudinal direction of the diaper are arranged at the ends of the free pieces 15. When wearing the paper diaper, the free pieces 15 of the auxiliary gathers AG are folded and reversed toward the respective both sides of the diaper so as to lay the auxiliary gathers on outer surfaces of flat gathers FG. By raising the auxiliary gathers AG, the flat gathers FG are put in close contact with the skin surface.
