Abstract: A welding work measurement system enables accurate measurement of a positional relation between respective parts. Therefore, a welding work measurement system includes a photodetection unit that detects light generated by a plurality of markers attached to a torch for welding a welding object or light reflected by the plurality of markers, a marker position acquisition unit that acquires marker position data that is three-dimensional coordinate data on the markers on the basis of the light detected by the photodetection unit, and a torch position acquisition unit that acquires torch position data that is three-dimensional coordinate data on the torch on the basis of the marker position data.