Curtain airbag device

In order to provide a curtain airbag device and a guide unit which allow quick deployment of a curtain airbag (1) when an inflator (3) is activated, the curtain airbag (1) is deployed downward. During the deployment, the rear portion of the curtain airbag (1) is guided by a guide rod (5) via a link strap (7). The curtain airbag (1) is provided with a first vertical chamber (30) extending along the guide rod (5) from the upper edge to the lower edge of the curtain airbag (1). A first opening area (A) of an upper portion of the first vertical chamber (30) is, for example, five to ten times greater than a second opening area (B) of a gas-entrance portion for a vertical chamber (34) and a bag chamber (44), which are adjacent to the first vertical chamber (30).