PURPOSE: To produce an optical recording medium having an Al reflecting film which hardly deteriorates by environmental conditions by using the ion beam sputtering method (IBS method).

CONSTITUTION: Beams consisting of only plus ions obtd. by discharging inert gas are made to collide with a target containing at least both of Al and Ta. Then, particles emitted from the target are deposited on a resin substrate. For example, a polymethyl methacrylate substrate for a video disk having 30cm diameter and 1.2mm thickness is mounted in an IBS device, which is once evacuated to 10-5Pa. Then, the pressure in the device is maintained at about 10-2Pa while gaseous Ar is being supplied. An electric current is supplied to a filament to produce a discharge state. An Ar plus ion current is applied on an Al-Ta alloy target to sputter alloy particles to deposit on the polymethyl methacrylate substrate to form a reflecting film of 30nm thick. Thus, the optical recording medium is produced.