A method for a diagnosis of an offset of a resolver of an electric machine, comprising: acquiring a predetermined offset of a resolver associated with said electric machine; in a first transient, supplying an excitation current to the phases of said electric machine so as to determine the injection of an exploring excitation current on an axis of minimum reluctance (d) of the electric machine in a rotating two-phase reference system (d-q) associated with a rotor of said electric machine, in which the position of said axis of minimum reluctance (d) is determined as a function of said predetermined offset of the resolver; as a consequence of said excitation current, determining a current established on the axis of minimum reluctance (d) and a current established on an axis in phase quadrature (q) with respect to the axis of minimum reluctance, as a function of the current detected on the phases of said electric machine; characterized in that it further comprises: in a second and in a third transient, respectively, supplying an excitation current to the phases of said electric machine so as to determine the injection of an exploring excitation current on said axis of minimum reluctance (d) of the electric machine, in which the position of said axis of minimum reluctance (d) is determined as a function of a modified offset of the resolver, said offset of the resolver being modified by a predetermined amount of deviation, in excess, respectively in defect with respect to the predetermined offset of the resolver; diagnosing the correspondence of an actual offset of the resolver with the predetermined offset of the resolver if the current established on the axis of minimum reluctance (d) in the first transient is higher than the current established on the axis of minimum reluctance (d) in the second or third transient, or if the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the first transient is lower than the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the second or third transient, or diagnosing an error in the predetermined offset of the resolver if the current established on the axis of minimum reluctance (d) in the first transient is lower than the current established on the axis of minimum reluctance (d) in the second or third transient, or if the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the first transient is higher than the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the second or third transient. acquiring a predetermined offset of a resolver associated with said electric machine; in a first transient, supplying an excitation current to the phases of said electric machine so as to determine the injection of an exploring excitation current on an axis of minimum reluctance (d) of the electric machine in a rotating two-phase reference system (d-q) associated with a rotor of said electric machine, in which the position of said axis of minimum reluctance (d) is determined as a function of said predetermined offset of the resolver; as a consequence of said excitation current, determining a current established on the axis of minimum reluctance (d) and a current established on an axis in phase quadrature (q) with respect to the axis of minimum reluctance, as a function of the current detected on the phases of said electric machine; in a second and in a third transient, respectively, supplying an excitation current to the phases of said electric machine so as to determine the injection of an exploring excitation current on said axis of minimum reluctance (d) of the electric machine, in which the position of said axis of minimum reluctance (d) is determined as a function of a modified offset of the resolver, said offset of the resolver being modified by a predetermined amount of deviation, in excess, respectively in defect with respect to the predetermined offset of the resolver; diagnosing the correspondence of an actual offset of the resolver with the predetermined offset of the resolver if the current established on the axis of minimum reluctance (d) in the first transient is higher than the current established on the axis of minimum reluctance (d) in the second or third transient, or if the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the first transient is lower than the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the second or third transient, or diagnosing an error in the predetermined offset of the resolver if the current established on the axis of minimum reluctance (d) in the first transient is lower than the current established on the axis of minimum reluctance (d) in the second or third transient, or if the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the first transient is higher than the current established on the axis in phase quadrature (q) with respect to the axis of minimum reluctance in the second or third transient.