PURPOSE: To realize the optimum flight control by generating the command for controlling pitch rate or acceleration according to the magnitude of the pilot input.

CONSTITUTION: A controlled variable variation type command conversion device 3 is equipped with a command selection part 31, and determines the gain constant K according to the magnitude of the pilot input. The command selection part 31 generates the pitch rate command uc1 and the acceleration command uc2, on the basis of the gain constant K. A conversion filter 32 converts the acceleration command uc2 to the pitch rate command uc3. An addition calculation part 33 adds the pitch rate commands uc1 and uc3, and outputs the result to a control part 2 for controlling the airframe 1.