The spunbonded nonwoven fabric uses fibers of thermoplastic resin, and when the water pressure resistance is repeatedly measured according to ISO811, the second resistance value measured after the second time with respect to the first water pressure resistance measured at the first time. The water pressure decreases by a predetermined water resistance of a predetermined pressure or less, the first water pressure resistance is 160 mmH 2 O or more, and the predetermined pressure is 30 mmH 2 O or less.スパンボンド不織布は、熱可塑性樹脂の繊維を用いており、ＩＳＯ８１１に準拠して耐水圧を繰り返し測定した場合に、一回目に測定された第一耐水圧に対する二回目以降に測定された第二耐水圧の低下分が所定圧以下である所定の耐水性を有し、第一耐水圧が１６０ｍｍＨ2Ｏ以上であり、所定圧が３０ｍｍＨ2Ｏ以下である。
