In a seat (1), a leg (30) is secured to a seat cushion (2) and is formed by four walls of a first wall (40) to a fourth wall (46), in which the first wall (40) facing a vehicle floor (60) and the second wall (42) facing the first wall (40) are fastened together to the vehicle floor (60) via a bolt (70) and a nut (72). A bush (50) capable of preventing the leg (30) from being crushed by the fastening-together action is positioned in the leg (30). A flange (54) is formed in a periphery of one end of the bush (50) and is interleaved between the first wall (40) of the leg (30) and the vehicle floor (60). The second wall (42) of the leg (30) is interleaved between a head portion of the bolt (70) and the other axial end of the bush (50).