A headrest stay includes a pair of first stay-composing parts extending in top and bottom directions of a seat back while supported by the seat back, the first stay-composing parts being arranged in different positions in a direction of vehicle width; and a second stay-composing part connecting specific parts of the first stay-composing parts in the direction of the vehicle width, the specific parts extending straight in the top and bottom directions of the seat back. The specific parts face a head of an occupant seated on the seat. A portion of the second stay-composing part, which portion is between the one specific part and the other specific part in the direction of the vehicle width, is not located further forward than the specific parts, and at least part of the portion is located further rearward than the specific parts.