Seal plates are mounted to and extend from a rim of a frame body to an inner surface of a casing so as to prevent short pass of exhaust gas. When the amount of the change of the temperature sensor output value is equal to or smaller greater than the threshold, the occupation ratio is not updated and the background temperature is updated by using the occupation ratio at the time one sampling period before. The apparatus includes a retrieval mechanism to remove a bottom one of said sheets of paper from the stack, and a deionizer that reduces static electricity in the vicinity of the stack. The input unit is connected to the combustion chamber, for inputting a high-pressure fuel in the combustion chamber and producing a predetermined pressure inside the combustion chamber.