To stabilize combustion control in a combustion device in manufacturing combustion equipment.

A volume flow rate of wood wastes is calculated on the basis of the information from a supply feeder 12 for quantitatively supplying wood wastes from a supply hopper 11 to a vertical roller mill 30 side, a weight flow rate of the wood wastes is measured on the basis of the information from a measurement belt conveyor disposed between the supply feeder 12 and the vertical roller mill 30, a bulk specific gravity as a specific gravity of weight and volume of the wood wastes is calculated by utilizing the weight flow rate and volume flow rate, an estimated moisture content of the wood wastes is calculated on the basis of the bulk specific gravity, an absolute drying flow rate representing a flow rate in an absolute drying state of the wood wastes is calculated by utilizing the estimated moisture content and weight flow rate, and the control relating to the supply of wood wastes from the supply hopper 11 to a combustion boiler 40 is performed according to a result of the calculation.