An internal structural reinforcement element for fuselages, where the internal structural reinforcement element has a longitudinal direction adapted for its location in the longitudinal direction of the fuselage and a transversal direction perpendicular to its longitudinal direction, wherein the internal structural reinforcement element comprises: - an outer reinforcement element, - an inner reinforcement element, located internally to the outer reinforcement element in the transversal direction of the internal structural reinforcement element, - the outer reinforcement element and the inner reinforcement element having a tubular shape with their longitudinal axis in accordance with the longitudinal direction of the internal structural reinforcement element, - an intermediate element, located between the outer reinforcement element and the inner reinforcement element in the transversal direction of the internal structural reinforcement element, the internal structural reinforcement element being characterised in that - both reinforcement elements (1, 2) are manufactured from resin-impregnated fibre placed respectively in a first male mould with the shape of the outer reinforcement element and in a second male mould with the shape of the inner reinforcement element and removed from the first male mould and from the second male mould so that the resin-impregnated fibre takes the form of the outer reinforcement element and of the inner reinforcement element, and in the intermediate element being manufactured from pre-impregnated composite material by ∘ placing the inner and outer reinforcement elements (1, 2) in a mould, the inner reinforcement element being located internally to the outer reinforcement element in a direction transversal to the internal structural reinforcement element, in such a way that a transversal hollow is defined between both reinforcement elements (1, 2), ∘ filling the transversal hollow between the inner and outer reinforcement elements (1, 2) with pre-impregnated composite material, forming the intermediate element, and ∘ performing a compression moulding of the assembly, to obtain the structural reinforcement element. - an outer reinforcement element, - an inner reinforcement element, located internally to the outer reinforcement element in the transversal direction of the internal structural reinforcement element, - the outer reinforcement element and the inner reinforcement element having a tubular shape with their longitudinal axis in accordance with the longitudinal direction of the internal structural reinforcement element, - an intermediate element, located between the outer reinforcement element and the inner reinforcement element in the transversal direction of the internal structural reinforcement element, the internal structural reinforcement element being characterised in that - both reinforcement elements (1, 2) are manufactured from resin-impregnated fibre placed respectively in a first male mould with the shape of the outer reinforcement element and in a second male mould with the shape of the inner reinforcement element and removed from the first male mould and from the second male mould so that the resin-impregnated fibre takes the form of the outer reinforcement element and of the inner reinforcement element, and in the intermediate element being manufactured from pre-impregnated composite material by ∘ placing the inner and outer reinforcement elements (1, 2) in a mould, the inner reinforcement element being located internally to the outer reinforcement element in a direction transversal to the internal structural reinforcement element, in such a way that a transversal hollow is defined between both reinforcement elements (1, 2), ∘ filling the transversal hollow between the inner and outer reinforcement elements (1, 2) with pre-impregnated composite material, forming the intermediate element, and ∘ performing a compression moulding of the assembly, to obtain the structural reinforcement element. ∘ placing the inner and outer reinforcement elements (1, 2) in a mould, the inner reinforcement element being located internally to the outer reinforcement element in a direction transversal to the internal structural reinforcement element, in such a way that a transversal hollow is defined between both reinforcement elements (1, 2), ∘ filling the transversal hollow between the inner and outer reinforcement elements (1, 2) with pre-impregnated composite material, forming the intermediate element, and ∘ performing a compression moulding of the assembly, to obtain the structural reinforcement element.