Side airbag apparatus

A side airbag apparatus for being installed in a seat of a vehicle, the side airbag apparatus comprising:

• an airbag having a front portion, in which a front chamber is formed, a rear portion, in which a rear chamber is formed, and a partition, which partitions the front chamber and the rear chamber from each other;
• an inflation fluid generator, which is accommodated in the rear chamber and supplies inflation fluid to the airbag;
• a communication passage, which is formed in the partition to connect the front chamber and the rear chamber to each other;
• and
• a pressure regulating valve provided in the communication passage, wherein, at an early stage of a supply period during which the inflation fluid generator supplies the inflation fluid to the airbag, the pressure regulating valve is closed to restrict flow of the inflation fluid from the rear chamber to the front chamber via the communication passage, and wherein the pressure regulating valve is opened during the supply period to permit the inflation fluid to flow therethrough, wherein
• the front portion of the airbag is folded toward the inflation fluid generator by roll-folding, in which the airbag front portion is repeatedly folded in one direction,
• the rear portion of the airbag is folded toward the inflation fluid generator by accordion-folding, in which the direction of folding is alternately changed, and
• the roll-folded airbag front portion and the accordion-folded airbag rear portion are located in front of the inflation fluid generator.