PURPOSE: To restrict any reaction between the fine powder coal and oxygen and prevent toxication of carbon monoxide or spontaneous combustion by a method wherein inactive gas is fed into the layer of fine powder coal stored in the closed tank and the air in the layer is replaced with the inactive gas.

CONSTITUTION: After the fine powder coal 3 is fed into the tank 1, an opening/ closing valve 6 is opened. Then, the inactive gas is fed into the layer of fine powder coal 3 from the blowing port nozzle 5 arranged an appropriate location of the lower part of tank 1, namely at a position lower than X/L=0.6, thereby the air in the tank 1 is discharged out of the tank 1 through the fine powder coal supplying pipe 8 and the air in the layer of fine powder coal 3 is replaced with the noble gas. Then, L is depth of the layer of the fine powder coal 3 and X is a distance ranging from the upper surface of the layer to the nozzle 5.