This composite stretchable member (10) has a plurality of affixing parts (14) for affixing an elastic member (13) to two sheet materials (11, 12), the affixing members being arranged discontinuously in the direction along which the elastic member (13) extends. The composite stretchable member (10) has, between two affixing parts (14) which are adjacent relative to the direction in which the elastic member (13) extends, a non-affixed part (16) wherein the elastic member (13) is not affixed to the two sheet materials (11, 12). Sections of the two sheet materials (11, 12) located between the adjacent affixing parts (14) move away from each other to form a pleat (15). The pleat (15) has a space (S) defined by the two sheet materials (11, 12). The cross-sectional area of the space (S) reaches the maximum value thereof when the elongation rate of the composite stretchable member (10) is 50% or less.本發明之複合伸縮構件(10)沿著彈性構件(13)所延伸之方向間斷性地具有複數個將彈性構件(13)與2片片材(11，12)固定之固定部(14)。複合伸縮構件(10)於沿著彈性構件(13)所延伸之方向相鄰之固定部(14)之間具有未將彈性構件(13)與2片片材(11，12)固定之非固定部(16)。位於相鄰之固定部(14)間之2片片材(11，12)朝相互遠離之方向移動而形成褶皺(15)。褶皺(15)具有由2片片材(11，12)劃分形成之空間(S)。空間(S)之截面積構成為於複合伸縮構件(10)之伸長率為50%以內時獲得最大值。
