An arc welding system includes an arc welding portion that executes an arc welding, an arc welding power supply that supplies a weld voltage and a weld current to the arc welding portion, an analyzer including analyzer circuitry that performs a frequency analysis on a time series waveform of at least one of the weld voltage and the weld current and generates frequency spectral data, and a determiner including determiner circuitry that obtains a welding state of a welding work by the arc welding portion based on the frequency spectral data generated by the analyzer.