PURPOSE: To make it possible to eliminate a distortion during the exhaust operation of a cathode-ray tube, by heating to make the temperature of metallic supporters at the portion buried in an insulating support glass higher than the softening point of the glass.

CONSTITUTION: The temperature of the portions of metallic supporters 5f and 6d fixed to a cathode 5 and the first electrode 6 respectively, which are buried in insulating support glasses 7 consisting of a boronsilicon oxide glass, is made higher than the softening point of the insulating support glasses 7, and they are heated at about 840°C at the maximum for a specific time to satisfy the exhaust requirement. In this case, although about 840°C is pointed here, any temperature higher than the softening point of the insulating support glass 7 will do to eliminate the distortion during the exhaust operation of the cathode- ray tube.