Plural regions are defined within a main wing by a plurality of spars and ribs. Of these regions, predetermined regions extending from a main wing connecting portion of the pylon to an internal space of a leading edge skin are used as wiring/piping accommodating chambers for collectively accommodating wiring and piping which provide communication between an engine and a fuselage, a predetermined region adjacent to parts of the wiring/piping accommodating chambers is used as a landing device accommodating chamber for accommodating a landing device and predetermined regions adjacent to other parts of the wiring/piping accommodating chambers are used as fuel tanks. Thus, the maintainability is improved as compared with the case where the wiring and the piping are distributed within the main wing. In addition, because the wiring/piping accommodating chambers are isolated from the landing device accommodating chamber and the fuel tanks, the operational reliability can be improved.