In a non-volatile logic circuit, a first input electrode and a second input electrode are formed on a semiconductor layer and interposed between an electric current source electrode and an output electrode in a plan view. The first input electrode is next to the second input electrode along the a direction orthogonal to the direction between the electric current source electrode and the output electrode. A method of operating the non-volatile logic circuit includes a step of writing one state selected from four states by applying voltages to the first input electrode and the second input electrode, respectively, and a step of measuring current generated by applying the voltage between the electric current power electrode and the output electrode to determine on the basis of the current, which of the high or low resistant state the non-volatile logic circuit has.