Abstract: A spare keys and retaining card set for automobiles and/or for other purpose locks mainly consists of a plurality of spare keys and a retaining card. Each spare key may be inset into the retaining card within a key shaped hollow and may be easily removed out of the hollow and the card, accordingly, for use by the user. The retaining card has a size similar to that of a name card and can be put into a wallet or a pocket for easy carry. Whenever the original key is lost or is not carried with the user, the spare key may timely resolve the problem to open a door.