To provide a gas chromatography, whereby a minute amount of nitrogen gas component in argon gas or oxygen gas can be quantitatively analyzed with good detection sensitivity, and a gas chromatograph utilizable in the gas chromatography.

In the method, a TCD(terminal conductivity detector) is used as a detector 4, and molecular sheaves are used as a separating column 3, so that a nitrogen gas component of a minute amount is argon gas or oxygen gas introduced by a carrier gas is quantitatively analyzed. Helium gas or hydrogen gas is used as the carrier gas, and the gases are separated at a first column 3a. A part of the argon gas or oxygen gas discharged earlier than the nitrogen gas component is removed beforehand, and the gas discharged subsequently is passed and separated again through a second column 3b before introduced into the detector 4.