A walk-in operation lever (2) is installed within the surface of a bracket (3) of a seat cushion by using a support shaft and is installed so as to be next to a reclining operation lever (1) attached to a reclining lock operation shaft (5) installed between the bracket (3) of the seat cushion and a bracket (4) of a seatback. Both operation levers (1, 2) are linked with the reclining lock operation lever (5) by a link mechanism in which blank action links (12, 14) of the respective operation levers are installed. The blank action links (12, 14) do not allow operation by either one of the levers to be transmitted to the other.