Device for measuring corrosion in a metallic structure or a structure comprising at least one metallic reinforcement, said device comprising: - at least one assembly that comprises: • a metallic part intended to be mechanically secured to the structure, said metallic part extending in a longitudinal direction and being able to undergo stresses under the effect of corrosion and/or a thermomechanical variation; • transduction means comprising an optical fibre, the optical fibre being fixed to the metallic part in a prestressed state under compression so as to undergo the stresses suffered by the metallic part, said transduction means being able to modify light propagating in the optical fibre under the effect of the stresses applied to the optical fibre; - measurement and processing means for measuring and processing the spectral responses supplied by the transduction means of said at least one assembly; the device being characterised in that the metallic part of said at least one assembly has an alternation of first and second portions, arranged in the longitudinal direction of the metallic part, each of the first and second portions being associated with at least one of the transduction means and only the first portions being covered with a layer of corrosion-protection material, so that the spectral responses supplied by the transduction means associated with the first portions are able to translate the application of a thermomechanical stress to the first portions, while the spectral responses supplied by the transduction means associated with the second portions are able to translate the application of a thermomechanical stress and/or a corrosion to the second portions, said layer of corrosion-protection material comprising a groove in which the optical fibre is housed; and the device being characterised in that the measurement and processing means further comprise means for comparing the spectral responses supplied by the transduction means associated with the first portions and those supplied by the transduction means associated with the second portions, in order to establish a corrosion profile of the metallic part. - at least one assembly that comprises: • a metallic part intended to be mechanically secured to the structure, said metallic part extending in a longitudinal direction and being able to undergo stresses under the effect of corrosion and/or a thermomechanical variation; • transduction means comprising an optical fibre, the optical fibre being fixed to the metallic part in a prestressed state under compression so as to undergo the stresses suffered by the metallic part, said transduction means being able to modify light propagating in the optical fibre under the effect of the stresses applied to the optical fibre; • a metallic part intended to be mechanically secured to the structure, said metallic part extending in a longitudinal direction and being able to undergo stresses under the effect of corrosion and/or a thermomechanical variation; • transduction means comprising an optical fibre, the optical fibre being fixed to the metallic part in a prestressed state under compression so as to undergo the stresses suffered by the metallic part, said transduction means being able to modify light propagating in the optical fibre under the effect of the stresses applied to the optical fibre; - measurement and processing means for measuring and processing the spectral responses supplied by the transduction means of said at least one assembly;