An occupant protection device which causes less discomfort to an occupant after danger is avoided. When danger is detected (estimated collision time t is less than t1), a seat is adjusted to set the inclination angle of a seatback within a predetermined appropriate range. After that, when the danger is avoided, the inclination angle of the seatback is adjusted a predetermined amount so that the occupant is separated from a seat belt. This eliminates situations in which the tension of the seat belt is kept increased even after the danger is avoided, and as a result, discomfort to the occupant is suppressed.