Abstract: An inertial sensor having an inner stator and an outer rotor that are electrostatically coupled together by mobile sensor arms and fixed sensor arms. The rotor is connected to a calibration microactuator comprising four sets of actuator elements arranged one for each quadrant of the inertial sensor. There are two actuators making up each set. The actuators are identical to each other, are angularly equidistant, and each comprises a mobile actuator arm connected to the rotor and bearing a plurality of mobile actuator electrodes, and a pair of fixed actuator arms which are set on opposite sides with respect to the corresponding mobile actuator arm and bear a plurality of fixed actuator electrodes. The mobile actuator electrodes and fixed actuator electrodes are connected to a driving unit which biases them so as to cause a preset motion of the rotor, the motion being detected by a sensing unit connected to the fixed sensor arms.