PURPOSE: To facilitate masking of an object to be metallized, by performing metallizing after providing a pair of masking jigs formed by an elastic member that covers the specified width from the edge of the side and both faces of an object to be metallized.

CONSTITUTION: Masking jigs 12, 12 are attached from both faces of a ceramic element 11, and placed on a receiving base 15 and one face of the ceramic element 11 is metallized by a metallizing device 16 to form a metallized layer 13. The ceramic element 11 is inverted at once and metallized again. Masking jigs 12, 12 are attached from both sides of the ceramic element 11. Slanted parts 12b, 12b are butted at the joint of the both forming a space 14. As slanted parts 12b, 12b are provided with relief, they can be superposed.