A gas turbine control apparatus, etc. are provided by which combustion fluctuation, even if arising in plural frequency bands, can be effectively suppressed. If the combustion fluctuation arises in plural frequency bands, corresponding to a predetermined priority order, adjustment is done so that the combustion fluctuation of the frequency band of a high priority order is suppressed. If the gas turbine state changes after the adjustment, this is reflected on a data base 30. If no sufficient data is stored yet in the data base 30 for any the reason, such as immediately after installation of the gas turbine, correction is made using data of countermeasures based on data of another same type gas turbine contained in a basic data base 31 and data of countermeasures based on experiences of skilled adjusting operators contained in a knowledge data base 32. Also, in a stabilized operation, operation condition may be varied so that an optimal operation condition is automatically searched.