A polycrystalline silicon producing method comprising: applying electric current to a silicon seed rod in a reactor so as to heat the silicon seed rod; supplying raw material gas including chlorosilanes to the silicon seed rod; and depositing polycrystalline silicon on a surface of the silicon seed rod to be grown as a rod, wherein a pressure in the reactor is equal to or greater than 0.4 MPa and equal to or less than 0.9 MPa, the method includes a first process and a second process, in the first process, the surface temperature of the rod is maintained at a predetermined range by adjusting the current value of the electric current applied to the silicon seed rod, the predetermined range being a temperature range at which a temperature of the center portion of the rod can be maintained at a predetermined temperature while having an effect of promoting the deposition of polycrystalline silicon, the predetermined temperature being lower than the melting point of polycrystalline silicon and being a temperature at which meltdown does not occur in the connecting portion between the silicon seed rod and the connecting member, and the raw material gas is supplied while maintaining a supply amount of chlorosilanes per square millimeter of the surface of the rod to be equal to or greater than 2.0×10 -7 mol/sec/mm 2 and equal to or less than 3.5×10 -7 mol/sec/mm 2 until the temperature of the center portion of the rod reaches the predetermined temperature, and in the second process, after the temperature of the center portion of the rod reaches the predetermined temperature, the electric current applied to the silicon seed rod is set to be a previously determined current value corresponding to the rod diameter and the supply amount of the raw material gas per square millimeter of the surface of the rod is decreased so as to maintain the surface temperature and the temperature of the center=portion of the rod to be within the predetermined ranges, respectively. applying electric current to a silicon seed rod in a reactor so as to heat the silicon seed rod; supplying raw material gas including chlorosilanes to the silicon seed rod; and depositing polycrystalline silicon on a surface of the silicon seed rod to be grown as a rod, wherein a pressure in the reactor is equal to or greater than 0.4 MPa and equal to or less than 0.9 MPa, the method includes a first process and a second process, in the first process, the surface temperature of the rod is maintained at a predetermined range by adjusting the current value of the electric current applied to the silicon seed rod, the predetermined range being a temperature range at which a temperature of the center portion of the rod can be maintained at a predetermined temperature while having an effect of promoting the deposition of polycrystalline silicon, the predetermined temperature being lower than the melting point of polycrystalline silicon and being a temperature at which meltdown does not occur in the connecting portion between the silicon seed rod and the connecting member, and the raw material gas is supplied while maintaining a supply amount of chlorosilanes per square millimeter of the surface of the rod to be equal to or greater than 2.0×10 -7 mol/sec/mm 2 and equal to or less than 3.5×10 -7 mol/sec/mm 2 until the temperature of the center portion of the rod reaches the predetermined temperature, and in the second process, after the temperature of the center portion of the rod reaches the predetermined temperature, the electric current applied to the silicon seed rod is set to be a previously determined current value corresponding to the rod diameter and the supply amount of the raw material gas per square millimeter of the surface of the rod is decreased so as to maintain the surface temperature and the temperature of the center=portion of the rod to be within the predetermined ranges, respectively.