A moving granular bed dust removal and reaction apparatus using glanular reaction agent as a granular bed material comprises a generally cylindrical, air-tight vessel disposed vertically, which has a gas outlet port, a reaction agent supply port and a reaction agent storage portion in an upper portion thereof, a gas inlet port, a gas chamber connected to the gas inlet port and a reaction agent passage defined in the gas chamber by a louver device in an intermediate portion and a lower portion having a regulatable discharge device. The reaction agent passage of the intermediate portion is communicated with a lower end of the reaction agent storage portion form a single column of reation agent. The regulatable discharge device regulates the moving speed of granular reaction agent supplied through the reaction agent supply port and allows it to move down by gravity to fill the single reaction agent column while filtering and adsorbing dust and toxic substances contained in upwardly moving gas therethrough.