A glass panel unit includes a first pane of glass, and a second pane of glass facing the first pane of glass with both of them spaced a predetermined interval apart. It is provided with a sealant between the panes of glass, joined to them in an airtight manner, and an interior space sealed with them and the sealant. It is provided with a first spacer in the interior space so as to be in contact with the panes of glass, and a second spacer disposed in the interior space so as to be in contact with only one of the panes of glass and out of contact with another thereof.