There is provided an occupant protection device for protecting an occupant seated on a seat, including: an airbag folded and accommodated in a bag shape made of a flexible sheet material; and a holding belt portion that is wrapped around a hip of the occupant and holds the folded airbag. The airbag is configured to, when the airbag is activated, allow an inflation gas to flow thereinto, and inflate to protrude forward and upward from the holding belt portion, and includes an upper body restraining surface capable of restraining an upper body of the occupant, on a rear surface side, when inflation is completed, and a vehicle body side member abutting surface that abuts against a vehicle body side member provided in front of the seat to be capable of ensuring a reaction force of the airbag when the occupant is restrained, on a front surface side.