Multi-bit flash memory device and memory cell array thereof

A multi-bit flash memory device and a memory cell array thereof are provided to assure compatibility of memory cells with different number of bits stored per cell. A plurality of memory blocks is allocated in a page. A plurality of memory cells is arranged on the crossing region of a plurality of bit lines and a plurality of word lines arranged in each block. At least two memory cells with different number of bits stored per cell are connected to each bit line.