The device according to the invention for estimating the impedance of an ground connection, the ground connection being connected to the ground of an alternating electric network (14) comprising a phase connected to an electric phase conductor and a neutral connected to an electric neutral conductor, comprises: an electrical component having a predetermined value impedance positioned between the phase conductor and the ground connection; a first sensor capable of measuring a first value of a first property between the phase conductor and the ground connection and a second value of the first property; a second sensor capable of measuring a first value of a second property between the neutral conductor and the ground connection and a second value of the second property; and a computation member computing the impedance of the ground connection.