PURPOSE: To make tunnel current exhibit strong non-linearity against control voltage by a potential structure wherein carrier's localization is formed in the direction of barrier layer's thickness and also in one direction independent of that direction, within the barrier layer.

CONSTITUTION: To the first electrode 5 for supplying a carrier through the first semiconductor layer 2 on a substrate 1, a barrier layer 3 which is a barrier for the carrier is connected. In the barrier layer 3, carrier's localization state is formed of a cubic quantum dot 3a in the thickness direction of the barrier layer 3 and also in one direction independent of that direction. Then to the barrier layer 3, through the second semiconductor layer 4, the second electrode 7 for absorbing the carrier is connected. By this, a tunnel multiple-input element is realized as a high performance element.