A manufacturing method of a glass panel unit, comprising: an adhesive disposing step of disposing a thermal adhesive to have a frame shape on a first panel including at least a first glass pane; a pillar disposition step of disposing a plurality of pillars on the first panel, each of the plurality of pillars including three resin layers (71, 72, 73) stacked on each other; an opposite disposition step of disposing a second panel to face the first panel, the second panel including at least a second glass pane; an inside space forming step of heating a glass composite including the first panel, the second panel, and the thermal adhesive to melt the thermal adhesive so as to form an inside space, the inside space being surrounded by the first panel, the second panel, and a melted substance of the thermal adhesive except for an exhaust path which allows gas to be exhausted to an outside space; a pressure reducing step of exhausting the gas in the inside space to reduce a pressure in the inside space; and a reduced-pressure space forming step of sealing the inside space with a reduced pressure in the inside space being maintained to form a reduced-pressure space hermetically sealed, wherein in each of the plurality of the pillars, a first resin layer of the three resin layers is in contact with the first panel, the first resin layer having a contact area in contact with the first panel, a second resin layer of the three resin layers is in contact with neither the first panel nor the second panel, a third resin layer of the three resin layers is in contact with the second panel, the third resin layer having a contact area in contact with the second panel, the contact area of the first resin layer is the same as the cross-sectional area of the second resin layer, and the contact area of the first resin layer and the cross-sectional area of the second resin layer are smaller than the contact area of the third resin layer. an adhesive disposing step of disposing a thermal adhesive to have a frame shape on a first panel including at least a first glass pane; a pillar disposition step of disposing a plurality of pillars on the first panel, each of the plurality of pillars including three resin layers (71, 72, 73) stacked on each other; an opposite disposition step of disposing a second panel to face the first panel, the second panel including at least a second glass pane; an inside space forming step of heating a glass composite including the first panel, the second panel, and the thermal adhesive to melt the thermal adhesive so as to form an inside space, the inside space being surrounded by the first panel, the second panel, and a melted substance of the thermal adhesive except for an exhaust path which allows gas to be exhausted to an outside space; a pressure reducing step of exhausting the gas in the inside space to reduce a pressure in the inside space; and a reduced-pressure space forming step of sealing the inside space with a reduced pressure in the inside space being maintained to form a reduced-pressure space hermetically sealed, wherein in each of the plurality of the pillars, a first resin layer of the three resin layers is in contact with the first panel, the first resin layer having a contact area in contact with the first panel, a second resin layer of the three resin layers is in contact with neither the first panel nor the second panel, a third resin layer of the three resin layers is in contact with the second panel, the third resin layer having a contact area in contact with the second panel, the contact area of the first resin layer is the same as the cross-sectional area of the second resin layer, and the contact area of the first resin layer and the cross-sectional area of the second resin layer are smaller than the contact area of the third resin layer. a first resin layer of the three resin layers is in contact with the first panel, the first resin layer having a contact area in contact with the first panel, a second resin layer of the three resin layers is in contact with neither the first panel nor the second panel, a third resin layer of the three resin layers is in contact with the second panel, the third resin layer having a contact area in contact with the second panel, the contact area of the first resin layer is the same as the cross-sectional area of the second resin layer, and the contact area of the first resin layer and the cross-sectional area of the second resin layer are smaller than the contact area of the third resin layer.