PURPOSE: To identify whether a destination to be guided is a target or a nontarget and to inhibit guiding of a projector in the case of the nontarget in an optically guiding system for guiding the projector toward the target.

CONSTITUTION: A transponder 21 for transmitting an optical pulse train (c) having a predetermined identification code when it receives a radiated pulse (a) to be radiated from a laser transmitter 13 of an aircraft 12 is provided on a ground runner 14. An identifier 22 for identifying whether the runner 14 is a target or a nontarget based on the train (c) is provided on a projector 11 to inhibit guiding of the projector 11 in the case of the nontarget.