An apparatus for controlling a gas-turbine aeroengine is configured to calculate a fuel command to supply fuel based on a calculated desired rotational speed of a low-pressure turbine calculated from an operation angle of a thrust lever installed at an aircraft cockpit pilot's seat, determines whether it is a time point for outputting a command to open/close a bleed-off valve equipped at a high-pressure compressor connected to a high-pressure turbine and to supply the fuel command based on the time point when it is determined to be the time point for outputting the command to open/close the bleed-off valve.