To provide a combustion method capable of stably combusting gas with a low calorific value without using combustion assist gas with high oxygen concentration in a combustion burner.

In the combustion burner, an opening for injecting each of a fuel gas and the combustion assist gas or injecting a premixed gas of the fuel gas and the combustion assist gas to generate a gas swirl flow in a combustion chamber is formed on the inner wall surface of the tubular combustion chamber having an opened tip. When a gas with a calorific value of 800 kcal/Nm3 or less is used as the fuel gas, hydrogen is added (however, including a case where it is added as a hydrogen-containing gas) to the fuel gas before being injected into the combustion chamber and/or the fuel gas injected into the combustion chamber so that the condition that the hydrogen concentration of the fuel gas after the hydrogen is added is 5 vol% or less and the calorific value is less than 900 kcal/Nm3 is satisfied.