A flash memory device is provided. The flash memory device includes a memory cell array and a pre-charge unit. The pre-charge unit, coupled to a plurality of bit lines corresponding with the memory cell array, pre-charges the bit lines to a predetermined voltage during a pre-charge stage. The pre-charge unit includes a voltage stabilizing unit to provide a constant current to the bit lines. Due to the voltage stabilizing unit, in a programming process, the voltage applied to the bit lines which are not related with programming may not drop as a result of current leakage. Therefore, the memory cells except the memory cell to be programmed are kept in cut off state, without a current passing. As a result, interference with the memory cells which are not to be programmed may be effectively avoided and the accuracy of programming may be improved.