Abstract: A device for automatic control of an electro-erosion machine comprises a sensing unit for sensing the impedance of the interelectrode gap and developing a signal proportional to resistance of an interelectrode gap, a reference voltage source, said unit and said source being connected to a drive feeding a tool electrode, a transmitter for determining an a-c component of interelectrode gap resistance connected to the output of the signal separation unit and a circuit for regulating the flow of working fluid, said transmitter being connected to the input of said circuit, while the output of said circuit is coupled to the working member of a mechanical flow regulation system.