To enable only the owner of a password reproduce his or her forgotten password without memorizing the password itself.

When a plurality of passwords are inputted to a confidential information reproducing device, code words constituted of Reed-Solomon codes corresponding to those passwords are generated, and only check symbols are stored, and the passwords themselves are not stored but erased. The check symbols provide the correcting capabilities of the vanishing errors for at least one password. When the passwords are forgotten any recallable password is inputted so that the forgotten passwords can be reproduced by correcting the vanishing errors by using the check symbols.