Seat pad, method of molding the same, and mold

A seat pad including a foam, such as a polystyrene foam, disposed on the back side thereof is provided which makes no abnormal noise and is easy to mold.  Also provided are a method of molding the seat pad and a mold for molding.  The seat pad (1) comprises a seat-pad main body (10), a molded foam (20) disposed on the back side of the seat-pad main body (10), and a supporter material (30) with which the molded foam (20) is covered.  The molded foam (20) has been disposed on the back side of a side-supporting part (4) and the bottom surface of this molded foam (20) has been covered with the supporter material (30) constituted of a nonwoven fabric, etc.  Since the molded foam (20) has been covered with the supporter material (30), the molded foam (20) is prevented from making an abnormal noise when the foam slides on the seat frame, etc.