PURPOSE: To prevent an aircraft motion from receiving effects of a gun firing, and improve a gun hit precision by controlling to offset both of a yawing moment and a side force generated by the gun firing by giving an instruction to a rudder and a controller for a separately provided direction system.

CONSTITUTION: Firing of a gun 2 is performed by pushing a gun trigger 6 provided at a control lever 5, when a firing instruction is outputted to the gun 2 form a gun controller 7 when the optimum timing and other conditions are satisfied. When a signal informing that the firing of the gun 2 has been performed is transmitted by a gun firing sensor to a control device 3, a control quantity determined by control laws is determined, it is transmitted to a rudder actuator 8 and a vertical canard actuator 9, and a control quantity corresponding to it is secured. Disturbance by both a yawing moment and a side force generated by the gun firing can thus be offset, and a gun hit precision can be improved.