A frame-shaped groove is formed on a panel adhering part of a sealing board, a paste including low melting point glass powder is buried in the groove, and a frame-shaped glass paste layer is formed. A solvent included in the glass paste layer is volatilized for solidification, and a low melting point glass frame is provided. Then, the low melting point glass frame protruded on the surface of the sealing board is removed, and the surface of a plane including the surface of the adhering part of the sealing board is flattened. A low heat resistant layer is formed on the flattened adhering plane of the sealing board. The sealing board is arranged to face an element board at a prescribed interval, laser beams are applied on the low melting point glass frame through the element board, and the area is heated. Thus, the low melting point glass rises, and the sealing board is welded with the element board.