A sanitary napkin (1) comprises an absorbing body (2). The absorbing body (2) includes a fluid-permeable top sheet (3), a fluid-impermeable back sheet (4), and an absorber (5) arranged between the top sheet (3) and the back sheet (4). The napkin comprises a cover sheet (8) for covering the surface of the top sheet (3). A circumferential edge region (8P) of the cover sheet (8) is joined to the absorbing body (2). A plurality of flaps for fixing the absorbing body (2) to underwear are sectionalized by a sectionalizing line (9) in the central region (8C) of the cover sheet. At the time of use, the flaps are folded in the folding regions and are expanded so as to be fixed to the underwear. The flaps include a front flat (10F) and a rear flap (10B) that expand in the back-and-forth direction, and a left flap (10L) and a right flap (10R) that expand in the right-and-left direction.