A stabilization network and a semiconductor device having the stabilization network wherein the stabilization network includes an active element having a negative resistance accompanying a high frequency negative resistance oscillation; and a tank circuit composed of a resistance connected to a main electrode of the active element, an inductance and capacitance which are connected in parallel with the resistance and synchronize with an oscillating frequency of the high frequency negative resistance oscillation, wherein the stabilization network is performed for suppressing a negative resistance accompanying a Gunn oscillation and obtaining stable and highly efficient power amplification.