A backup unit comprises a first storage means containing at least one program and a setup file in which the operating environment of that program is written; a second storage means used when the first storage means has a fault; a duplication means for duplicating the program and the setup file contained in the first storage means, into the second storage means; and an identifier conversion means for converting identifiers included in the setup file of the first storage means and relating to the first storage means, into identifiers relating to the second storage means, when the duplication is performed. Therefore, when the operation of an information processor is stopped due to a fault in the first storage means, the second storage means enables temporary operation of the information processor. In addition, it is possible to employ, as the second storage means, a recording medium that is lower in price and writing speed than the first storage means.