Provided is an automatic reduction apparatus for pre-treating a sample for radiocarbon dating, and more particularly, an automatic reduction apparatus for pre-treating a sample for radiocarbon dating capable of preventing peripheral devices of a liquid nitrogen container from being cooled due to scattering of liquid nitrogen supplied to the liquid nitrogen container of a carbon dioxide collector and preventing the peripheral devices from being heated by heat of a reaction furnace at the time of heating the reaction furnace of a reduction reactor.