A headrest supporting structure is provided with a lower spring and an upper spring, which are located at different positions in the vertical direction of a seat. The structure elastically supports a headrest stay with the springs. When a stopper section, which changes the position in the front-back direction in accordance with pivoting of the headrest, comes into contact with a support bracket, further pivoting of the headrest is restricted. The stiffness of the upper spring located relatively distant from the stopper section in the seat vertical direction is higher than that of the lower spring located closer to the stopper section.