Flash memory and method for improving reliability of flash memory

The invention provides a flash memory and a method for improving the reliability of the flash memory. The method for improving the reliability of the flash memory comprises the steps of during a writing period, applying a first turn-on voltage, a first voltage and a second voltage to a gate structure, a first source/drain and a second source/drain of a transistor respectively through a word line, a bit line and a reference bit line, thereby executing a writing action on a flash memory unit; and during a test period after the writing period, applying a second turn-on voltage, a third voltage and a fourth voltage to the gate structure, the first source/drain and the second source/drain of the transistor respectively through the word line, the bit line and the reference bit line, thereby executing a test action, wherein the first turn-on voltage is higher than the second turn-on voltage, the first voltage is higher than the second voltage, and the fourth voltage is higher than the third voltage. By implementing