An arrangement including a curtain airbag device, a vehicle body member, a roof lining and a B-pillar garnish, the curtain airbag device comprising: a curtain airbag (1; 1'; 1''; 1'''; 1B) for being deployed in an interior of a vehicle cabin, wherein a folded body of the curtain airbag (1; 1'; 1''; 1'''; 1B) is disposed in a space between the vehicle body member and a side edge portion of the roof lining; and an inflator that inflates the curtain airbag (1; 1'; 1"; 1"'; 1B), wherein the curtain airbag (1; 1'; 1''; 1'''; 1B) includes a gas introduction portion positioned at a level above the B-pillar garnish, the gas introduction portion extending upward from a curtain airbag main body, a gas being introduced from the inflator to the curtain airbag main body through the gas introduction portion, and wherein, in a state in which the curtain airbag (1; 1'; 1''; 1'''; 1B) is folded into the folded body thereof, the gas introduction portion is disposed on a side surface of the folded curtain airbag main body, the side surface being located to face the vehicle body member, characterized in that the folded body of the curtain airbag (1; 1'; 1''; 1'''; 1B) includes an upper, pleat-folded portion and a lower, roll-folded portion, the pleat-folded portion being sized so that a length in an up-down direction of the pleat-folded portion having been deployed is equal to or larger than a distance between the folded body of the curtain airbag (1; 1'; 1''; 1'''; 1B) and an upper end of the B-pillar garnish, so that upon airbag deployment the pleat-folded portion inflates to move the roll-folded portion down beyond an upper end of the B-pillar garnish prior to inflation of the roll-folded portion, and that the gas introduction portion is folded into an even number of layers which extend along a side surface of the folded curtain airbag main body including both the pleat-folded portion and the roll-folded portion, wherein the gas introduction portion is bent such that it is also disposed on a lower surface of the folded curtain airbag main body including both the pleat-folded portion and the roll-folded portion. a curtain airbag (1; 1'; 1''; 1'''; 1B) for being deployed in an interior of a vehicle cabin, wherein a folded body of the curtain airbag (1; 1'; 1''; 1'''; 1B) is disposed in a space between the vehicle body member and a side edge portion of the roof lining; and an inflator that inflates the curtain airbag (1; 1'; 1"; 1"'; 1B), wherein the curtain airbag (1; 1'; 1''; 1'''; 1B) includes a gas introduction portion positioned at a level above the B-pillar garnish, the gas introduction portion extending upward from a curtain airbag main body, a gas being introduced from the inflator to the curtain airbag main body through the gas introduction portion, and wherein, in a state in which the curtain airbag (1; 1'; 1''; 1'''; 1B) is folded into the folded body thereof, the gas introduction portion is disposed on a side surface of the folded curtain airbag main body, the side surface being located to face the vehicle body member, characterized in that the folded body of the curtain airbag (1; 1'; 1''; 1'''; 1B) includes an upper, pleat-folded portion and a lower, roll-folded portion, the pleat-folded portion being sized so that a length in an up-down direction of the pleat-folded portion having been deployed is equal to or larger than a distance between the folded body of the curtain airbag (1; 1'; 1''; 1'''; 1B) and an upper end of the B-pillar garnish, so that upon airbag deployment the pleat-folded portion inflates to move the roll-folded portion down beyond an upper end of the B-pillar garnish prior to inflation of the roll-folded portion, and that the gas introduction portion is folded into an even number of layers which extend along a side surface of the folded curtain airbag main body including both the pleat-folded portion and the roll-folded portion, wherein the gas introduction portion is bent such that it is also disposed on a lower surface of the folded curtain airbag main body including both the pleat-folded portion and the roll-folded portion.