This study was performed to test the flame retardancy of zelkova sarrata-based materials by the treatment of ammonium salts. Zelkova sarrata plate was soaked by the treatment with three 20 wt% ammonium salt solutions consisting ammonium chloride (AMSL), monoammonium phosphate (MAPP), and diammonium phosphate (DAPP), respectively, at the room temperature. After the drying specimen treated with chemicals, combustion properties were examined by the cone calorimeter (ISO 5660-1). When the ammonium salts were used as the retardant for zelkova sarrata, the flame retardancy improved due to the treated ammonium salts in the virgin zelkova sarrata. However the specimen shows increasing CO over virgin zelkova sarrata and It is supposed that toxicities depend on extents. Also, the specimen with ammonium salts showed the higher total smoke release (TSR) than that of virgin plate. Of specimens treated with ammonium salts the ammonium chloride handled the test side was considered a improved inhibitory effect of combustion.