We developed a novel method to protect logging information more securely. The method, named NIGELOG, produces multiple backups of the logging information, hides them in arbitrary directories, and periodically moves these backups to other directories. Also, NIGELOG can au- tomatically restore the original logging informa- tion by using the backups even if the original le is altered or deleted by intruders. NIGELOG is implemented as a C++ class library with some standard software libraries and does not require additional hardwares such as write-once media. It is easier to apply NIGELOG to UNIX appli- cations which produces log-files.