Disclosed herein may be a side airbag apparatus and a method of manufacturing the same. The side airbag apparatus may include: an outboard sheet part disposed on a side portion of a vehicle body; an inboard sheet part laminated to an interior side of the outboard sheet part and formed such that a first peripheral part located on an opposite side of a gas injecting part is longer than a second peripheral part located adjacent to the gas injecting part; a push chamber formed such that a folding length of the first peripheral part is longer than that of the second peripheral part; a folding seam part seaming a folded part of the first peripheral part; and a peripheral seam part seaming a peripheral part of the outboard sheet part, a peripheral part of the inboard sheet part, and the first peripheral part of the push chamber all together.