Abstract: The invention is a lamp quality judgement apparatus and judgement method which judge quality by detecting the state of gas sealed in an electric lamp such as a gas-filled incandescent lamp, etc. in which gas with an Argon-Nitrogen mixture as its main component is sealed. More particularly, a lamp in which such gas is sealed is classified as a good product or as a bad product by imposing a high DC voltage or a high AC or pulsed voltage with a comparatively low frequency of 1 kHz or less across the lamp's valve and filament coil to produce discharge and emission, in the lamp, of a light in a wavelength region in the vicinity of 560 nm and judging the radiation state in this 560 nm light spectrum, i.e., the state of discharge in the lamp.