Provided is a fluidized bed gasification method wherein an amount of solid particles to be circulated in a fluidized bed combustion furnace is controlled to enhance gasification efficiency in the furnace.It is the fluidized bed gasification method with fluidized bed combustion and gasification furnaces 30 and 43, char and solid particles produced upon gasification of raw material 51 in the gasification furnace 43 being circulated to the combustion furnace 30. A circulated amount of the solid particles in the combustion furnace is controlled by varying the same in a range of 6 to 30 with respect to an air flow rate, thereby facilitating heat transmission to the raw material 51.