The process for producing polycrystalline silicon by feeding a reaction gas containing a silane gas and a hydrogen gas into a reaction vessel equipped with silicon core members erected on the electrodes, heating the silicon core members by flowing an electric current thereto to a temperature at which silicon deposits, forming polycrystalline silicon rods by allowing the formed silicon to deposit on the silicon core members, and discharging the discharge gas after the reaction from the reaction vessel, wherein the discharge gas discharged from the reaction vessel is quenched so that the temperature thereof drops from 800° C. down to 500° C. in not longer than 0.1 second.