Abstract: The present invention discloses a sense amplifier circuit for reading-out information stored in a memory cell, include in a flash memory device having a main cell array in which a plurality of memory cells are connected between a plurality of word lines and a plurality of bit lines comprises an auxiliary cell array in which a plurality of memory cells are connected between a plurality of word lines and a bit line, a reference cell connected between a source voltage and the ground and in which a drain thereof is connected to a common source line of the auxiliary cell array, and a sense amplifier the input terminals of which are connected to the common source line of the auxiliary cell array and the bit line of the main cell array, respectively.