PURPOSE: To take in a sufficient amount of air to an air intake device even though the posture angle of a flying object and the flying direction are different.

CONSTITUTION: An air intake duct 1 opened to the front side of the plane body and extended to the rear side, openings 2 provided at both side walls of the air intake duct, a valve 3 to open and close the openings 2 being rotated by the air flow, and a stopper 5 provided at the side wall of the air intake duct 1 and to prevent the rotation of the valve 3 to the outer sides of the openings 2 have been furnished.