As biomass has become increasingly important, wood pellets are becoming more widely used, and the storage of wood flour, which is the raw material of wood pellets, has become inevitable. The purpose of this study was to reduce the economic losses from fires during storage of porous combustible materials. To achieve this purpose, the authors analyzed and compared the wood flour loss rate between the use of water and the use of wetting agents to extinguish a deep-seated fire through a scale model experiment. To do this, the authors measured the penetration amount of the water and dilute solutions of wetting agent, the weight change of the wood flour holder, and the emissions on a real time basis when that spray amount was the same. Furthermore, the authors analyzed the calorific value and combustion gas to examine the reusability of the wood flour with the added wetting agent. This study quantitatively demonstrated that the active use of wetting agents in wood flour storage fires dramatically reduced the fire loss rate of raw materials and resulted in early fire extinguishing, which minimizes companies’ economic loss.