A method of producing an undercover for a vehicle includes: placing a first component including a planar surface, second components including planar surfaces, and a third component including a cavity with an opening in a surface such that the third component is sandwiched between the second components with the surfaces of the second components and the surface of the third components opposed to the surface of the first component; placing the sheet that is softened between the first component and the second components; vacuuming the sheet with the first component until a first surface thereof is pressed against the surface of the first component; bringing the surfaces of the second components into contact with a second surface of the sheet; and moving the third component toward the first component until the cavity is filled with a portion of the sheet while maintaining the first component and the second components thereat.