Patent ID: 8391047

Claim:
A method of executing a forming operation to variable resistance elements each provided between one of a plurality of first wirings and one of a plurality of second wirings, respectively, the forming operation to render the variable resistance element capable of transitioning its resistance value, the method comprising: applying a required voltage between the first and second wirings and changing the first wiring to a floating state, wherein the applying the required voltage includes: applying a first voltage to a selected first wiring, the selected first wiring being one of the first wirings, applying a second voltage lower than the first voltage to a non-selected first wiring, the non-selected first wiring being another one of the first wirings, applying a third voltage lower than the first voltage to a selected second wiring such that the required voltage to execute the forming operation to the variable resistance element is applied between the selected first wiring and the selected second wiring, the selected second wiring being one of the second wirings, and changing the selected first wiring to the floating state when the third voltage is applied to the selected second wiring.