A seat reclining device includes: a first bracket including an accommodating portion being open to an outer side of a seat in a width direction; a second bracket rotating with respect to the first bracket; a cam rotating with respect to the first bracket; a spring accommodated in the accommodating portion and biasing the cam; a pawl moved in a radial direction of the first bracket based on the rotation of the cam and engaged with the second bracket; and a cover covering the spring, wherein the cover is mounted on the accommodating portion and an outer surface of the cover on the outer side corresponds to an outer surface of the first bracket on the outer side or is positioned inside the outer surface of the first bracket in the width direction of the seat.