To provide a method capable of preventlng cards such as a credit card and a cash card housed in a wallet and a card container from being illicitly be skimmed by a non-contact type skimming apparatus.

In this method, sealing materials are coated separately to be easily folded or cut so as to be easily used to be inserted or stuck to the wallet or the card container. As a material effective for skimming prevention, a metal such as gold, silver, copper, iron, stainless steel, lead, brass, etc. are exenplified. The film is obtained by sandwiching metallic thin foil such as gold foil with thin plastic films and applying a coating thereon for preventing corrosion and breakage.