An electromechanical actuator to operate a using device of an internal combustion engine, in particular for a turbocharger adjusting system; wherein the electromechanical actuator comprises: a housing formed through a lower element and holding a closed seat, which is provided with a symmetry axis and with a lid, which is in turn provided with a through opening coaxial to the symmetry axis; a shaft, which is coaxial to the symmetry axis and comprises a lower portion that engages the seat and an upper portion whose diameter is uneven and smaller than the diameter of the lower portion; the upper portion is divided into a segment joining it to the lower portion, a central segment and an upper segment projecting from the opening to operate the using device; an electric motor, which, through a transmission, causes the rotation of the shaft and is housed in a seat formed in the lower element; and a tubular bushing, coaxial to the symmetry axis and interposed between the lower portion and the seat; the actuator being characterized in that the lower portion is provided with a peripheral annular groove, which is designed to house an annular sealing gasket interposed between the lower portion and the seat, wherein an upper surface of the annular sealing gasket defines a support surface for the bushing, and in that an upper surface of the bushing is coplanar with an upper surface of the seat, thus defining a striker for a first element of the transmission; and in that the actuator further comprises an annular reinforcement gasket, which is co-moulded in the lid, has an annular shape and is coaxial to the symmetry axis; wherein the annular reinforcement gasket comprises an appendage, which projects into a compartment defined between the lower element and the lid, thus getting into a space available between the central segment of the shaft and a portion made of magnetic material of the first element. a housing formed through a lower element and holding a closed seat, which is provided with a symmetry axis and with a lid, which is in turn provided with a through opening coaxial to the symmetry axis; a shaft, which is coaxial to the symmetry axis and comprises a lower portion that engages the seat and an upper portion whose diameter is uneven and smaller than the diameter of the lower portion; the upper portion is divided into a segment joining it to the lower portion, a central segment and an upper segment projecting from the opening to operate the using device; an electric motor, which, through a transmission, causes the rotation of the shaft and is housed in a seat formed in the lower element; and a tubular bushing, coaxial to the symmetry axis and interposed between the lower portion and the seat; the actuator being characterized in that the lower portion is provided with a peripheral annular groove, which is designed to house an annular sealing gasket interposed between the lower portion and the seat, wherein an upper surface of the annular sealing gasket defines a support surface for the bushing, and in that an upper surface of the bushing is coplanar with an upper surface of the seat, thus defining a striker for a first element of the transmission; and in that the actuator further comprises an annular reinforcement gasket, which is co-moulded in the lid, has an annular shape and is coaxial to the symmetry axis; wherein the annular reinforcement gasket comprises an appendage, which projects into a compartment defined between the lower element and the lid, thus getting into a space available between the central segment of the shaft and a portion made of magnetic material of the first element.