A side airbag includes two main-body fabrics superimposed to have one sides opposed to each other and including a textile having 400 dtex or less yarn, 200 g/m2 or less weight, and 2,000 or more cover factor, thermosetting silicone placed at least one sides of the two fabrics, and solventless addition room-temperature-vulcanizing adhesive silicone interposed between the two fabrics at a junction and having 20 or less JIS-A hardness and 800% or more initial fractural elongation after cure.