A fusion memory device and method that is capable of storing binary data in a compressed format and reading out the compressed binary data in a decompressed format is provided. The fusion memory device includes a main memory for storing data in a compressed format; a secondary memory for buffering binary data to be written within and read from the main memory; and a memory controller having a pair of compressor and decompressor. The memory controller controlling the secondary memory to buffer the binary data downloaded from a host device and the compressor compressing the binary data buffered with the secondary memory in a writing mode. The memory controller controlling the secondary memory to buffer the binary data read out from the main memory within the secondary memory and the decompressor decompressing the binary data buffered within the secondary memory in a reading mode.