Three or more elongated cover portion elastic members along a width direction are disposed in a gluteal cover portion of a back outer member. The gluteal cover portion is contracted in the width direction by the cover portion elastic members. The cover portion elastic member located closest to a waist opening is disposed at an end portion of the gluteal cover portion on the waist opening side. The cover portion elastic member located closest to a leg opening is disposed at an end portion of the gluteal cover portion on the leg opening side. When a central interval between the cover portion elastic member located closest to the waist opening and the cover portion elastic member located second from the waist opening is represented by dA, and the front-back direction length of the gluteal cover portion is represented by dE, dA>；0.5dE is satisfied.
