An entrained bed coal gasifier constructed so as to conduct two-stage reactions in a single gasification zone can be operated with high gasification efficiency by feeding coal and a gasifying agent through upper burners located at an upper portion from the half of the gasification section along the vertical direction and lower burners located at a lower portion from the half of the gasification section so as to make rotational flow respectively, the ratio of the amount of gasifying agent to the amount of coal at lower burners being larger than that of at the upper burners, the rotating circle diameter formed by the coal and gasifying agent injected from the upper burner being larger than that formed by the lower burner.