Side airbag apparatus

A side airbag apparatus comprising:

• a side airbag housed in a seat back of a seat of a vehicle in a state such that the side airbag is folded to have a reduced width in a front-rear direction of the vehicle, the side airbag configured to, when supplied with gas, be deployed and inflated toward a front side of the vehicle between an occupant seated on the seat and a body side portion of the vehicle,
• wherein the side airbag includes:
• a lower protection portion configured to protect a portion below a head portion of the occupant when the side airbag is deployed and inflated;
• and
• an upper protection portion positioned above the lower protection portion, protruding toward the front side of the vehicle than the lower protection portion, and configured to protect the head portion of the occupant, when the side airbag is deployed and inflated, and
• wherein the side airbag is folded so as to have the reduced width in the front-rear direction of the vehicle and housed in the seat back, in a state in which the upper protection portion is folded toward a lower side so as to be positioned on an outer side in a width direction of the vehicle with respect to the lower protection portion, and a portion, that protrudes toward the front side of the vehicle with respect to the lower protection portion, of the upper protection portion folded toward the lower side, is folded toward a rear side of the vehicle so as to be positioned on an inner side in the width direction of the vehicle with respect to the lower protection portion.