In a clip, first and second attachment portions are coupled by a coupling portion in an open state in which a seatback spring is able to pass between the first and second attachment portions in the radial direction of the seatback spring. The first and second attachment portions swing in mutually engaging directions. The first attachment portion is formed with a first placement portion, and the second attachment portion is formed with a second placement portion. The seatback spring can accordingly be placed between the coupling portion and either the first placement portion or the second placement portion. In this placed state, the seatback spring is retained in the clip by engaging an engagement claw of the first attachment portion with a peripheral edge portion of an engagement hole of the second attachment portion, enabling fixing to an attachment portion of a lower frame.