To prevent the leakage of the menstrual blood by providing a sanitary napkin used at the time of sleeping in the night during menstruation with a rod-like plug (or objects having the analogous functions thereof) which fits snugly into the natal cleft.

The plug which improves absorbability and is covered with material having water-proofness is attached to the rear part (the portion to be snugly fitted into the natal cleft) of the sanitary napkin, i.e., te portion of a main body 1, to close the natal cleft. The plug is formed like a rod of bout 50 mm in length and 15 mm in diameter and its shape is columnar, conical, triangle pole or triangle pyramid.