Provided are a resistive memory device and a method of the resistive memory device. The method of operating the resistive memory device includes performing a pre-read operation on memory cells in response to a write command; performing an erase operation on one or more first memory cells on which a reset write operation is to be performed, determined based on a result of comparing pre-read data from the pre-read operation with write data; and performing set-direction programming on at least some memory cells from among the erased one or more first memory cells and on one or more second memory cells on which a set write operation is to be performed.

Some embodiments include memory devices having a wordline, a bitline, a memory element selectively configurable in one of three or more different resistive states, and a diode configured to allow a current to flow from the wordline through the memory element to the bitline responsive to a voltage being applied across the wordline and the bitline and to decrease the current if the voltage is increased or decreased. Some embodiments include memory devices having a wordline, a bitline, memory element selectively configurable in one of two or more different resistive states, a first diode configured to inhibit a first current from flowing from the bitline to the wordline responsive to a first voltage, and a second diode comprising a dielectric material and configured to allow a second current to flow from the wordline to the bitline responsive to a second voltage.

A nonvolatile semiconductor memory device according to an embodiment includes: a semiconductor layer; a control gate electrode; and an organic molecular layer, which is provided between the semiconductor layer and the control gate electrode, and has organic molecules including a molecular structure described by a molecular formula (1). ##STR00001##