PURPOSE: To generate a call-on signal moved in the direction of an airframe to improve target pursuit ability by identifying the direction of the movement of a target by comparing a relative speed with the speed of a flying object and adding a bias signal in accordance with a relative distance to a steering instruction signal.

CONSTITUTION: A flying object consists of a steering instruction bias signal generator 17 for outputting a steering instruction compensation signal in which a bias quantity if added to an error signal in accordance with a relative distance signal, an adder 18 for adding the steering instruction signal to the steering instruction compensation signal to output a compensation steering instruction signal and the like. An optical system is locked on the target plume, and in the case where the distance of a flying object 21 and a target 22 is R1, a small- bias signal θ1 is output whereas in the case where the distance is R2 corresponding to a long relative distance, a bias signal θ2 is output which increases as the target approaches.