Disclosed is an apparatus and method of mirroring firmware and data of an embedded system. The embedded system mirrors a boot loader image, a kernel image, a RAM disk image and data that are stored on a main flash memory to be operated onto a secondary flash memory. Therefore, when a main flash memory does not normally work, the firmware and data that are stored on the main flash memory to be operated is mirrored onto the secondary flash memory, which prevents the loss of data and maintains the operation of the embedded system. As a result, it is possible to secure the reliability and operability of the system.