PURPOSE: To contrive the simplification of a mechanism and the reduction of space for housing a position changing device by constituting one part of a wing of a variable pressure air chamber with a member of high tensile rigidity serving as one side wall part of the upper and the bottom while with a member of low tensile rigidity serving as the other side wall part of the upper and the bottom.

CONSTITUTION: Variable pressure air chambers 1A and 1B are respectively provided between a leading edge part 3 of a wing 4 and its central part and between the central part of the wing and its trailing edge part 3 and constituted with a bottom wall 5 of a high tensile rigidity member while with an upper wall 6 of a low tensile rigidity member, and the upper and bottom walls 6 and 5 form one part of upper and bottom surfaces of the wing. In this way, when a pressure of gas in the variable pressure air chambers 1A, 1B is increased, the leading edge part 2 and the trailing edge part 3 are lowered to the bottom, and a section of the wing is deformed as the total unit so as to increase a protrusive camber. Thus, a shape of the wing can be changed by a simplified mechanism, further a wing structural weight and wing part position changing device enables its housing space to be decreased.