A method of manufacturing containers covered tightly with a protective sheet with a porous resin film layer or rubber film layer in-between.By the method of this invention, a resin solution or rubber solution is foamed mechanically in advance and the foamed layer made by the foamed resin film or the foamed rubber film then is covered with a heat shrinkable sheet which is heat shrunk tightly to the containers. The foamed layer does not shrink during the heating. Accordingly, the surface of the heat shrinkable sheet is free from waviness due to gas foaming of the covered layer during heat shrinking which has been the case with conventional methods. The method, therefore, does not affect the appearance or printing performance of the surface of the heat shrinkable sheet.