PURPOSE: To obtain not only a conspicuous interference effect by modulating an electron wave, but also the electronic wave can be modulated sufficiently in a quantum interference transistor without non-elastic scattering of electrons.

CONSTITUTION: The title transistor is provided with an electron transit layer 23 consisting of an AlGaAs barrier region 23A which is extended to a semiinsulative GaAs substrate 21, an AlGaAs graded region 23B, a GaAs well region 23C, an AlGaAs barrier region 23D, a GaAs well region 23C, an AlGaAs graded region 23E and an AlGaAs barrier region 23F. Also, an N-type AlGaAs electron-feeding layer 24 located on the electron transit layer 23, a source electrode 26 which is connected to the secondary carrier gas layer generated on the side of the electron transit layer 23 located in the vicinity of the interface between the electron feeding layer 24 and the electron transit layer 23, a drain electrode 27, a GaAs well region 23C, an AlGaAs barrier region 23D, and a gate electrode 28, which is located directly above the GaAs well region 23C, are provided.