A striking circuit of the pilot arc for plasma arc torches (25), comprising a low power impulse generator (27), suitable for striking the pilot arc between the cathode (28) and auxiliary anode (29), which is positioned inside the torch body (25) and kept separate from the direct current generator (20), which feeds both the pilot arc and the main arc, until the arc has been permanently struck; the separation of the part of the circuit in which the low power impulses are present is obtained by using an insulated inductor (37), with a ferrite separation nucleus between the feeder (21) and the torch body (25), and a discharger (41), situated in series with the impulse generator (27), associated with an oscillator and an amplifier, so as to obtain, between the high voltage outlet of the impulse generator (27) and the earth (31), high voltage impulses, having a frequency of about 250 kHz. The electromagnetic emissions are thus reduced during the functioning of the torch (25) and the whole system is more compact, reliable and functional, with respect to the known art.