In a seat reclining device, a spiral spring includes an inner end portion engaged with the cam, an outer end portion engaged with the lower arm, and a wound portion formed by winding and provided between the inner end portion and the outer end portion. The outer end portion of the spiral spring includes a straight line portion extending consecutively from the wound portion and an accommodating portion includes a guide recessed portion accommodating the straight line portion therein and being in contact with the inner peripheral side surface of the straight line portion and being in contact with the outer peripheral side surface of the straight line portion at a further outer end than the contact point with the inner peripheral side surface.