PURPOSE: To obtain the cover for a semiconductor device, having a transparent window through which the coming in and out of light is possible and possible to be sealed up by performing a welding such as a seam welding, etc., on vessels, by a method wherein the window made of transparent sapphire or hard glass is brazed to metal rings through the intermediary of a metals wax material.

CONSTITUTION: Metalized layers 6 are provided at the sealing part of a window 12 made of transparent sapphire or hard glass by a Mo-Mn method, etc., and metal rings 11 and the window 12 are brazed with a silver solder material 13. On vessels 2 adhered with a semiconductor element 4, a wire connection is performed and a cover is put, and the metalized layer 6 and the metal rings 11 for the cover are welded by a seam welding method. The cover can be applied for devices handling light too and the contents in the cover can be seen through, because the cover has a transparent window. No thermal stress is given to the semiconductor elements, because the brazing of the window and the metal rings are performed at a place where there exists no semiconductor element.