Provided is a method for producing a production gas and an apparatus using the same with which a load may be increased in biomass treatment and the quality of the production gas may be improved. According to the present invention, a raw material fluid (F2) containing a biomass (M1) is supplied from an upstream end (22a) toward a downstream end (22b) in a raw material passage (22) separated from the outside by a reaction tube wall (21), and the raw fluid (F2) of the raw material passage (22) is heated from the outer side of the raw material passage (22) through the reaction tube wall (21) by a first heating means (F1). The raw material passage (22) comprises a first gasification region (23) where a first gasification reaction occurs in which at least part of the biomass is gasified by heating conducted by the first heating means (F1), and a second gasification area (25) disposed closer to the downstream end (22b) than to the first gasification region (23). Additional heating of the raw material fluid (F2) is conducted by a second heating means (30) at the second gasification region (25).