An apparatus for separating carbon products from used tires includes a decomposing chamber into which used tires are charged, a nitrogen gas supply device that supplies nitrogen gas into the decomposing chamber, one or more magnetrons that generate microwave of predetermined frequency and one or more phase shifters that removes interference between microwaves generated by the magnetrons, a receiving plate that is adapted to receive carbon black and iron cores generated by the decomposing process, a tire support that is adapted to support used tires, an opening and closing device that opens or closes a door on which used tires are placed, conveyor belt that moves carbon black and iron cores to a desired location after decomposition is complete, and a cooling plate that is provided in an upper portion of the apparatus and cools down gaseous oil that is generated by decomposition by microwave into liquid oil.