The ultraviolet radiation generated during arc welding is a well-known cause of photokeratoconjunctivitis, and is also associated with dermatitis and skin cancer. Determining the ultraviolet radiation level of the various welding conditions is important for establishing protective measures for workers in the welding workplace.In this study, we measure the ultraviolet radiation generated by MIG welding of aluminum alloys using a digital inverter-type pulsed arc welding machine. In the experiment, the base metal is moved, and the welding torch and ultraviolet radiation detector are fixed to measure the ultraviolet irradiance. The measurement in one experiment is carried out for 40 seconds and repeated three times. The distance between the detector and the arc source is 500 mm.The following results were obtained; (1) the effective ultraviolet irradiance is strongly influenced by the amount of magnesium contained in aluminum alloys, and the magnesium in the welding wire contributes to the emission of ultraviolet radiation more than that in the base metal; (2) the effective irradiance is dependent on the angle of the welding direction and the angle from the base material and is the strongest near the face and cervix of the welding operator; and (3) the effective irradiance is significantly increased when the welding current is pulse-controlled.