The present invention relates to a
file system protection technology applied to an auxiliary storage device (20), and relates to a device and method for preventing or warning access to or modification of a
file system in advance, and protecting the
file system by confirming the user's permission when necessary. A control device (60) is connected to a
host interface (30), a data storage device (40), and a
user input device (50) to control the
operation mode of the auxiliary storage device or manage and protect protected file
system objects according to user commands. When the
operation mode of the auxiliary storage device is management mode, the user can specify the file
system object to be protected and set its protection method, and the user-set information is stored in a protected object
database (70). In
normal mode, when the host's access target is a file
system object uploaded to the protected object
database, a protection operation is performed with reference to the protection method of the protected object
database. In
normal mode, the host cannot access the protected object database (70) set by the user in the setting mode, thereby preventing malicious code from changing or destroying the protected object database (70).