PURPOSE: To improve acceleration performance at the time of abnormality by performing abnormality time control in accordance with accelerative and steady conditions of an engine even when an inlet temperature of a compressor turbine or an outlet temperature of an output turbine of the gas turbine engine is placed in an excessive value.

CONSTITUTION: A biaxial gas turbine engine is provided with a gas generator GG, combustor CC, variable nozzle VN and an output turbine PT of a separate shaft. Here an engine acceleration condition is detected in an engine acceleration detecting means 2 by detecting a temperature in a predetermined location of the gas generator GG by an engine temperature detecting means 1. A steady time engine control means 3, in which an engine temperature T is compared with the first preset temperature Ta, controls an opening αs of a variable nozzle VN in an opening direction, at the time of a relation where T≥Ta, and performs ordinary feedback control of the opening αs at the time of the relation where T≥Ta continued for less than a predetermined time and at the time of a relation where T<Ta. An acceleration time engine control means 4 controls the opening αs to a predetermined degree in an opening side, at the time of accelerating the engine, and also compares the engine temperature T with the second preset temperature Tc to perform control of changing the variable nozzle VN further to the opening side from the predetermined opening at the time of a relation T≥Tc.