PURPOSE: To prevent a decrease in a penetrating capacity and generation of ricocheting by deciding an approaching direction of a missile by sensing an infrared ray irradiated from a target, measuring a distance to a target ship by sensing a reflected wave by an active radar, and altering a flying route of the missile.

CONSTITUTION: A vertical length (a) and a lateral length (b) of a target ship are estimated by an infrared ray image of an infrared ray sensor, and its ratio is obtained. If the ratio is a predetermined threshold value (p) or less, an attack from a bow or a stern is decided. (b/a≤p). At a point X, an approaching direction is decided according to the image, at a point Y, a range is measured by a radar, and at a point Z, the flying route is altered. Thus, the approaching direction of a missile is varied, the missile is approached substantially perpendicularly to a side face of an upper surface of the target thereby to improve a penetrating capacity of the missile and to prevent generation of ricocheting.