Disposable diaper

1. A disposable diaper comprising:

a crotch portion;

a ventral-side portion extending toward the ventral side of the crotch portion;

a dorsal-side portion extending toward the dorsal side of the crotch portion;

an absorber in the crotch portion, the ventral-side portion, and the dorsal-side portion, and

a concave portion having no absorber and formed at a width-direction center of a width-direction slit,

wherein the absorber is divided in a front-back direction by the width-direction slit entirely extending in the width direction from left side edge to right side edge of the absorber and provided on at least one of front and back sides of the crotch portion, wherein the absorber in the crotch portion is in a same plane as the absorber in the ventral-side portion and the absorber in the dorsal-side portion, and

wherein the concave portion extends from a waist side edge of the with-direction slit and recesses toward a waist side of the disposable diaper, wherein width-direction both side edges of the concave portion are deformed to close the concave portion so that a portion of the absorber surrounding the concave portion is rounded along a surface of a wearer's body.

2. The disposable diaper according to claim 1 , wherein the concave portion is shaped in such a manner as to be narrower with increasing proximity to the waist side.

3. The disposable diaper according to claim 1 , comprising concave portion deformation elastic members that exert a contraction force in the width-direction to bring both side edges of the concave portion closer to each other.

4. The disposable diaper according to claim 3 , wherein the concave portion deformation elastic members are elongated elastic members that are arranged in such a manner as to curve toward the crotch portion and cross over the concave portion.

5. The disposable diaper according to claim 3 , comprising:

an outer body constituting individually or integrally a front panel and a back panel; and

an inner body that includes the absorber and is attached on an inner side of the outer body ranging from the front panel to the back panel, the outer body of the front panel and the outer body of the back panel being joined together at both side edges to form side seal portions, thereby forming a waist opening and a pair of right and left leg openings, wherein

fit elastic members are provided in the outer body from one side seal portion to the other side seal portion, and

a portion of the fit elastic members are arranged as the concave portion deformation elastic members in such a manner as to cross over the concave portion.

6. The disposable diaper according to claim 5 , wherein the fit elastic members at least in a width-direction intermediate portion overlapping the inner body are cut between side edges of the crotch portion and the concave portion to make the fit elastic members being cut non-contractible and to keep the concave portion deformation elastic members being contractible.

7. The disposable diaper according to claim 1 , wherein at least one of the width-direction slits is formed in such a manner that a clearance width becomes larger with increasing proximity to width-direction both sides.

8. The disposable diaper according to claim 1 , wherein an easily folded portion extending in a front-back direction is formed in a width-direction center of the absorber.