A headrest can be rotated with respect to a seatback, and support strength in a vertical direction of the headrest can be improved. In a vehicular seat, lower side curved surfaces of headrest supports, to which leg portions of a headrest are coupled, slide on lower ends of support brackets and upper side curved surfaces of the headrest supports slide on upper ends of the support brackets, whereby rotation of the headrest supports about an axis along a horizontal direction of a seatback with respect to the support brackets is guided. Further, the lower side curved surfaces touch the lower ends of the support brackets and the upper side curved surfaces touch the upper ends of the support brackets, whereby movement of the headrest supports in a vertical direction of the seatback with respect to the support brackets is suppressed.