To prevent damage to a ring-shaped product 1 without requiring a cutter or scissors in unpacking the product.

At a predetermined angular position of a product, Plastic films 3 and 4 are wound onto the outer peripheral surface, both side surfaces, and inner peripheral surface of the product to heat-seal and cut them along the outer peripheral surface and inner peripheral surface of the product, and at other angular positions of the product, plastic films are wound onto the inner peripheral surface, both side surfaces, and the outer peripheral surface of the product to heat-seal and cut them along the inner peripheral surface and outer peripheral surface of the product.