Resonant vibration energy harvester for optimizing the conversion of vibrational kinetic energy generated by an external source into electrical energy, the harvester comprising: a supporting housing capable of vibrating in response to the external source; and an electromagnetic generator coupled to the housing and having a resonance frequency, wherein the generator comprises: elastic means placed within the housing and fixed to a wall of said housing; at least one magnetic element, having a mass (m) and coupled to the housing by said elastic means, wherein said elastic means create a relative motion between the magnetic element and the housing itself and wherein the magnetic element is a permanent magnet and the resonance frequency of the electromagnetic generator is the mechanical resonance frequency of the magnetic element with respect to the housing; and a first conductive winding magnetically coupled to the magnetic element and fixed to the housing such that the vibrational kinetic energy generated by the external source determines a relative displacement (x) between the magnetic element and the first winding causing a potential difference to be generated at the ends of the first winding, characterized by the fact that the harvester further comprises a second conductive winding fixed to a non-vibrating support and being stationary with respect to said support and separated from the housing, wherein the distance between the first winding and the second winding is such as to make a mutual magnetic coupling between said first and second winding (14, 15) negligible; and control means connected to the ends of the second winding to introduce an electric current within the second winding and regulate the intensity of said electric current so as to adapt the resonance frequency of the electromagnetic generator to the vibration frequency associated to the vibrational kinetic energy generated by the external source. a supporting housing capable of vibrating in response to the external source; and an electromagnetic generator coupled to the housing and having a resonance frequency, wherein the generator comprises: elastic means placed within the housing and fixed to a wall of said housing; at least one magnetic element, having a mass (m) and coupled to the housing by said elastic means, wherein said elastic means create a relative motion between the magnetic element and the housing itself and wherein the magnetic element is a permanent magnet and the resonance frequency of the electromagnetic generator is the mechanical resonance frequency of the magnetic element with respect to the housing; and a first conductive winding magnetically coupled to the magnetic element and fixed to the housing such that the vibrational kinetic energy generated by the external source determines a relative displacement (x) between the magnetic element and the first winding causing a potential difference to be generated at the ends of the first winding, characterized by the fact that the harvester further comprises a second conductive winding fixed to a non-vibrating support and being stationary with respect to said support and separated from the housing, wherein the distance between the first winding and the second winding is such as to make a mutual magnetic coupling between said first and second winding (14, 15) negligible; and control means connected to the ends of the second winding to introduce an electric current within the second winding and regulate the intensity of said electric current so as to adapt the resonance frequency of the electromagnetic generator to the vibration frequency associated to the vibrational kinetic energy generated by the external source. elastic means placed within the housing and fixed to a wall of said housing; at least one magnetic element, having a mass (m) and coupled to the housing by said elastic means, wherein said elastic means create a relative motion between the magnetic element and the housing itself and wherein the magnetic element is a permanent magnet and the resonance frequency of the electromagnetic generator is the mechanical resonance frequency of the magnetic element with respect to the housing; and a first conductive winding magnetically coupled to the magnetic element and fixed to the housing such that the vibrational kinetic energy generated by the external source determines a relative displacement (x) between the magnetic element and the first winding causing a potential difference to be generated at the ends of the first winding, characterized by the fact that the harvester further comprises a second conductive winding fixed to a non-vibrating support and being stationary with respect to said support and separated from the housing, wherein the distance between the first winding and the second winding is such as to make a mutual magnetic coupling between said first and second winding (14, 15) negligible; and control means connected to the ends of the second winding to introduce an electric current within the second winding and regulate the intensity of said electric current so as to adapt the resonance frequency of the electromagnetic generator to the vibration frequency associated to the vibrational kinetic energy generated by the external source.