1. A method of implementing a memristor-based multilevel memory using a reference resistor array, the method comprising the steps of in a way making a resistance value of the memristor selected from among memristors of a memristor array equal to the reference resistance value of a node selected from among nodes of the reference resistor array, writing the reference resistance value in the selected memristor; and when the reference resistance value written in the selected memristor is deviated from the originally stored resistance value, restoring the resistance value of the selected memristor to the originally stored resistance value by making the resistance value of the selected memristor equal to the closest reference resistance value among all the nodes of the reference resistor array.