PURPOSE: To easily execute the detection and the display of welding condition and prevent the damage by transmitting the welding data detected with a toroidal coil through a transmitter by a wireless method, receiving with a receiving device and outputting to a data outputting part.

CONSTITUTION: The welding condition is detected in real time with the toroidal coil 2 and transmitted to the transmitter 3 and converted to digital welding data with an integral part 5, waveform processor 9, A/D converter 10 and data processor 11 in the transmitter 3 and wirelessly transmitted from a transmitting part 12. Sucessively, the welding data are received with a data receiving part 13 in the receiving device 4 and an analyzed data are calculated with a data output processor 14 and the welding data and various kinds of analyzed data are obtd. Further, these measured values and various kinds of analyzed data, etc., are stored in a data storing part 15 in the receiving device 4 and also, displayed with the data outputting part 16.