PURPOSE: To reduce the amount of char flying from a gasification part to a gas cooling part, by means of a cylinder, provided in the upper constricted part of the gasification part in the boundary part of the gasification part and the gas cooling part, and having the lower end protruding into the gasification part.

CONSTITUTION: A jet bed gasification furnace having a cylinder 15, e.g. made of ceramics, provided in the upper constricted part 11 of a gasification part 1, and having the lower end 16 protruding into the gasification part 1 by a length (S). A swirling current in the upper part of the gasification part 1 is kept and continued, and powdered coal is pressed to a refractory wall 14 of the gasification part 1 by the centrifugal force to flow down along the refractory wall 14. Thus, the powdered coal is separated from the rising current of the coal gas, and the flying thereof from the gasification part 1 to the gas cooling part 2 is prevented.