Abstract: A gas turbine apparatus is provided wherein a turbine is driven or rotated by burning a mixture of a fuel and compressed air and supplying a combustion gas generated by the combustion. A flameout determination unit is provided in the apparatus which is adapted to calculate the air/fuel ratio in the air/fuel mixture, correct the calculated air/fuel ratio to calculate a corrected air/fuel ratio which is substantially constant, compare the calculated corrected air/fuel ratio with a predetermined reference air/fuel ratio, and generate a signal indicative of occurrence of a flameout when the corrected air/fuel ratio is smaller than the reference air/fuel ratio.