Replacing hard disks as a storage device, NAND flash memories are now widely used on embedded systems due to a variety of advantages such as fast accessibility, low power consumption, solid durability and small form factor. However, the NAND flash memory cannot use existing file system for hard disks because of the physical difference between the NAND flash memory and hard disk drive. Consequently, the research of YAFFS(Yet Another Flash File System), a special file system for NAND flash memory, is actively going on. YAFFS file system reads a spare area of the entire block in order to find the header information on mounting and uses the header found to create the file system structure in random access memory(RAM). The mounting method like this has a drawback of increasing the mounting time in proportion to a size of flash memories, because it reads the spare area of the entire block. In this paper, to overcome this problem and thus reduce the mounting time, scanning only the spare area of header file that exists one in every files of each blocks is proposed instead of scanning entire page of NAND flash memories. Test result shows that the proposed approach reduces the mounting time by maximum of 34.78% than existing method of YAFFS file system.