Glass panel unit and inspection method thereof

1. An inspection method for a glass panel unit comprising a first glass panel;

a second glass panel placed opposite the first glass panel;

a seal with a frame shape placed between the first glass panel and the second glass panel to hermetically bond the first glass panel and the second glass panel to each other;

an evacuated space enclosed by the first glass panel, the second glass panel, and the seal; and

a gas adsorbent placed in the evacuated space and including a getter, the gas adsorbent being visible through at least one of the first glass panel and the second glass panel, and having properties of changing its color when adsorbing gas, the inspection method comprising steps of:

observing an original color of the gas adsorbent at a first time when the gas adsorbent is first placed into the evacuated space through at least one of the first and second glass panels;

observing a color of the gas adsorbent at a second time through at least one of the first and second glass panels, wherein the second time is after the first time by a predetermined time period; and

determining a degree of vacuum of the evacuated space to be low and the gas adsorbent to be inactive when the color of the gas adsorbent at the second time is changed from the original color at the first time.

2. The inspection method of claim 1 , wherein the degree of vacuum of the evacuated space is determined to be lower than 0.1 Pa when the color of the gas adsorbent at the second time is changed from the original color at the first time.