PURPOSE: To prevent the pollution of a sputtered film by using the same material for the target portion and target push portion of a target and applying a preliminary sputtering before the sputtering operation.

CONSTITUTION: The cathode 1 facing an anode is made into a magnetron type in which the cathode body 2 is provided with the magnet 3 and the overlying target 4, and the target consists of the target portion 5 in an erosion region and the target push portion 6 in the region other than the erosion region, both of which are made of the same material. Prior to the operation of sputtering, the magnet 3 is turned into nonoperative state and preliminary sputtering is applied. Thus, the whose surface of the target 3 is cleaned by sputter etching. Also, even by the subsequent sputtering, clean sputtered film can be obtained because the target portion and its push portion are made of the same material.