An occupant protection device protects an occupant seated on a seat, in which an airbag is held in a holding body disposed in a periphery of a hip portion of the occupant. The airbag has a bag main body, and a conduit portion that causes an inflating gas discharged from an inflator to flow into the bag main body. The bag main body is held in the holding body as a completely folded body, folded using a front-rear reduction folding such that a width dimension in a front-rear direction is reduced from a preliminary folded bag. The completely folded body is formed by a lower side rolled region, formed by a lower side region of the preliminary folded bag being wound from a lower edge side, being stacked on an upper side rolled region, formed by an upper side region of the preliminary folded bag.