PURPOSE: To eliminate the irregularity and lowering of brightness and also prevent the imperfection of airtightness by placing a sinter body of glass in annular form on the circumferential edge of the projection part of a lid member having a conical projection part at the center and then fusing the lid member in an exhaust hole hermetically.

CONSTITUTION: An annular glass sinter body 8 of PbO-B2O3 series is placed on the circumferential edge of the part 8 of a lid member 7 having a conical projection part at the center. And then the member 7 is placed on the top part of the movable type heater tower of an exhaust device, and the sinter body 8 is fused by directly heating with a heater 4. Next, when gas is adequately exhausted from a display tube 20, a tower 3 is raised and the part 6 of the member 7 is inserted into the exhaust hole 5 of the tube 20 and hermetically sealed. Then, the sinter body 8 may be easily arranged and at the same time the adhesion of evaporated glass components can be prevented, so that the irregularity and lowering of brightness due to the adhesion of glass to an electrode and the like can be eliminated. And also the sealing can be made at the center of the hole 5, so that the imperfection of airtightness can be prevented.