NOVELTY - The apparatus has a reactor whose inside is sealed with bell-jar and disk shaped base-plate (5). A gas supply nozzle (9) is arranged inside virtual concentric circle (C) formed in center of base-plate. The gas supply nozzles are arranged in center of base-plate while other gas supply nozzle is arranged in position of vertex of regular polygon internally-contacted in other virtual concentric circle. The gas flow rate control portion controls ejection source gas from gas supply nozzle to inside of bell-jar by flow rate of 150m/sec or more.    USE - Apparatus for manufacturing polycrystalline silicon used as raw material of single crystal silicon substrate for manufacturing semiconductor device and solar cell.    ADVANTAGE - Since the gas supply nozzles are arranged in center of base-plate while other gas supply nozzle is arranged in position of vertex of regular polygon internally-contacted in other virtual concentric circle, the circulation flows can be generated efficiently within the reactor and the high-speed reactive-gas flow in furnace can be achieved. The reactive-gas flow rate of the polycrystalline-silicon rod vicinity can be ensured and local raise of the gas temperature in reactor is prevented so that the heavy metal contamination is obtained when generation of powder and polycrystalline-silicon rod with projective abnormal precipitation can be eliminated by suppressing the popcorn generation on the surface of polycrystalline silicon.    DETAILED DESCRIPTION - The apparatus has base-plate that is provided with gas supply nozzle for supplying source gas to electrode pair for supplying electricity to silicon core wire and interior space of bell-jar. The height of interior space of bell-jar is 5m. The radius of other virtual concentric circle is 20-70cm. The diameter of gas emission hole of gas supply nozzle is 7-20 mm. An INDEPENDENT CLAIM is included for polycrystalline silicon manufacturing method involves depositing polycrystalline silicon on surface of silicon core wire except initial stage of silicon precipitation reaction.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the base-plate and source gas supply nozzle provided in the reactor.    Base-plate (5)    Reaction waste gas exit (8)    Gas supply nozzle (9)    Electrode (10)    Virtual concentric circle (C)