Lower end portions of an edge and another edge are fixed to a wire through pull-in cloths and a fixing member such that the pull-in cloths pull the lower end portions in toward the rear and into an opening (slit). This enables the edge and the another edge to be closed together in a state in which tension is applied to a front covering and a side covering. This enables the external appearance of a seatback to be preserved. Further, the edge and the another edge can be separated from each other, enabling a connector to be inserted into the opening from between the edge and the another edge, and the connector to be connected to an ISOFIX member. An inferior external appearance of the seatback can accordingly be suppressed while securing insertability of the connector.