A glass panel unit manufacturing method comprising: a glue arrangement step including arranging a hot glue on either a first panel or a second panel, the first panel including a first glass pane and having a predetermined degree of warpage being represented by an H/L ratio equal to or more than 0.2%, where L is the length as measured along the surface of the first panel and H is the magnitude of deviation as measured perpendicularly to the surface of the first panel, the second panel including a second glass pane; a pillar forming step including placing pillars on either the first panel or the second panel; an assembly forming step including forming an assembly including the first panel, the second panel, the hot glue, and the pillars and having an exhaust port provided through at least one of the first panel, the second panel, or the hot glue by arranging the second panel such that the second panel faces the first panel; a bonding step including bonding the first panel and the second panel together with the hot glue and thereby forming an internal space surrounded, except the exhaust port, with the first panel, the second panel, and the hot glue that has melted by heating the assembly with the first panel arranged to form an upper part of the assembly and the second panel arranged to form a lower part of the assembly; the bonding step being divided into a first temperature raising step, a first temperature maintaining step, and a first temperature lowering step according to temperature variations, wherein, in the temperature maintaining step, the first panel softens to a certain degree allowing at least one portion of said first panel to lower itself due to its own weight until said first panel is supported by all or almost all of the hot glue and the pillars, so as to significantly reduce or even eliminate the warpage of the first panel; an evacuation step including reducing pressure in the internal space by evacuation that involves exhausting a gas from the internal space; and a sealing step including creating a hermetically sealed evacuated space by closing the exhaust port and sealing the internal space while maintaining a reduced pressure in the internal space. a glue arrangement step including arranging a hot glue on either a first panel or a second panel, the first panel including a first glass pane and having a predetermined degree of warpage being represented by an H/L ratio equal to or more than 0.2%, where L is the length as measured along the surface of the first panel and H is the magnitude of deviation as measured perpendicularly to the surface of the first panel, the second panel including a second glass pane; a pillar forming step including placing pillars on either the first panel or the second panel; an assembly forming step including forming an assembly including the first panel, the second panel, the hot glue, and the pillars and having an exhaust port provided through at least one of the first panel, the second panel, or the hot glue by arranging the second panel such that the second panel faces the first panel; a bonding step including bonding the first panel and the second panel together with the hot glue and thereby forming an internal space surrounded, except the exhaust port, with the first panel, the second panel, and the hot glue that has melted by heating the assembly with the first panel arranged to form an upper part of the assembly and the second panel arranged to form a lower part of the assembly; the bonding step being divided into a first temperature raising step, a first temperature maintaining step, and a first temperature lowering step according to temperature variations, wherein, in the temperature maintaining step, the first panel softens to a certain degree allowing at least one portion of said first panel to lower itself due to its own weight until said first panel is supported by all or almost all of the hot glue and the pillars, so as to significantly reduce or even eliminate the warpage of the first panel; an evacuation step including reducing pressure in the internal space by evacuation that involves exhausting a gas from the internal space; and a sealing step including creating a hermetically sealed evacuated space by closing the exhaust port and sealing the internal space while maintaining a reduced pressure in the internal space.