A pump unit installed inside a wing, and a panel body constituting part of a wing structure portion forming a surface structure of the wing are provided. The pump unit includes a backup hydraulic pump that can supply pressure oil to an actuator when a loss or reduction occurs in the function of an aircraft central hydraulic power source and an electric motor that drives this pump. Except for at least the panel body, the wing structure portion is formed from fiber reinforced plastics. The panel body is formed of a metallic material.