Glass panel unit and glass window

A glass panel unit comprising

• a first panel including at least a first glass pane;
• a second panel arranged to face the first panel with a predetermined gap left with respect to the first panel and including at least a second glass pane;
• a sealing member arranged between the first panel and the second panel to hermetically bond the first panel and the second panel together;
• an internal space configured to form a reduced-pressure space by being sealed hermetically with the first panel, the second panel, and the sealing member;
• and
• a spacer arranged in the internal space so as to be in contact with the first panel and the second panel,
• the spacer including a plurality of resin layers that are stacked one on top of another in a facing direction in which the first panel and the second panel face each other, at least any two of the plurality of resin layers having different elastic moduli.