An aircraft nose structure includes a fuselage and a pressuretight bulkhead fixed at its periphery to the fuselage and transversely dividing the fuselage into a pressurized upper zone and an unpressurized lower zone for accommodating retractable nose landing gear. The pressuretight bulkhead includes a floor of the pressurized upper zone, and a substantially flat rear panel extending between a rear edge of the floor and the fuselage. The floor and the rear panel are fixed laterally to the fuselage. The fuselage includes an exterior wall and reinforcing transverse frames to which the exterior wall is fixed. In line with the pressuretight bulkhead, at least some of the transverse reinforcing frames extend along the outline of the pressurized upper zone and constitute members that reinforce the pressuretight bulkhead.