An aircraft comprising a wing box and a fuselage provided with a connecting device configured to be connected to the wing box and to transmit thereto stresses undergone by the fuselage during maneuvers of the aircraft are provided. The connecting device is formed by a keel beam and a keel beam panel connected to the beam via a connecting portion of the beam, that is moreover provided with a main portion extending in a first, generally longitudinal direction and a transfer portion extending in a second direction different from the first direction and configured to be connected to the box. The main, transfer and connecting portions are configured to direct a major part of the stresses received by the beam in the second direction and transmit said major part of the stresses to the box by compression.