METHOD OF OPERATING SEMICONDUCTOR MEMORY DEVICE

A semiconductor memory device includes a variable resistance memory element connected between first and second conductive lines intersecting each other, and a PN junction diode connected between the variable resistance memory element and the first conductive line. The method of operating the semiconductor device includes supplying the variable resistance memory element with a first directional current flowing from the second conductive line to the first conductive line by applying a first forward bias to the PN junction diode, and supplying the variable resistance memory element with a second directional current flowing from the first conductive line to the second conductive line by applying a reverse bias to the PN junction diode immediately after applying a second forward bias to the PN junction diode.