An apparatus for measuring an error in a resolver includes a first calculator that perform an inverse Park transform based on voltages Uq and Ud at an output of PI current regulators, and delivers voltage setpoint signals PWMA, PWMB, PWMC to a power stage via a line on which a DC voltage Ubus-dc is available. The power stage generates a three-phase system of voltages UA, UB, UC for energizing an electric machine. The apparatus also includes a signal processor that provides an angle measurement αm. Based on currents MesIA, MesIB, MesIC of the three phases, and on a rotor angle αr, a second calculator of the device delivers values MesId, MesIq used by the first calculator. A PI voltage regulator delivers an angle αc for correcting the error by regulating a setpoint value for the voltage Ud.