SIDE AIRBAG DEVICE AND METHOD FOR FOLDING BAG SECTION THEREOF

The present invention provides a side airbag device, in which an airbag lower portion including a loin protection portion is expanded generally right downward to expand and develop the loin protection portion quickly, so that at the time of a side crash of the vehicle, the airbag is located between the loins of the passenger and the door trim with certainty to protect the passenger, and a method for folding a bag section thereof. The airbag 42 includes an airbag upper portion 42U including a chest protection portion for protecting the chest of a passenger when the airbag 42 is developed and an airbag lower portion 42L including a loin protection portion for protecting the loins of the passenger when the airbag 42 is developed. The airbag 42 is accommodated in the state of being folded such that a bottom part of the airbag upper portion 42U and a top part of the airbag lower portion 42L overlap (OL) each other in a width direction of the vehicle, and such that a bottom end of the airbag lower portion 42L is located below a top end of the airbag lower portion 42L.