In a wing structure for an aircraft, a rib extends in a chord direction for connecting spars to each other with upper and lower stringer through holes through which stringers of skins pass being formed in upper and lower edges of the rib. A bead is formed on the rib so as to extend between the upper and lower stringer through holes. Upper and lower ends of the bead are formed into arcuate shapes so as to surround the upper and lower stringer through holes, respectively. Thus, it is possible to enhance the buckling strength of the rib against a shear load acting on the wing of the aircraft.