1. An apparatus for producing a silicon single crystal based on a Czochralski method provided with a chamber having a heater therein to heat a raw material and cooling means to cool the chamber by a coolant, the apparatus comprising:measuring means for measuring an inlet temperature, an outlet temperature, and a flow rate in a passage of the coolant to cool the chamber with flowing in the chamber;
calculating means for calculating a removed heat quantity from the chamber on the basis of the measured values of the inlet temperature, the outlet temperature, and the flow rate; and
heater power-controlling means for controlling heater power on the basis of the calculated value of the removed heat quantity,
wherein the heater power-controlling means is provided with a function for calculating a pattern of set values of heater power in a straight body forming process in the next pulling, on the basis of operation result data of the removed heat quantity from the chamber obtained through pulling a silicon single crystal, and
the pattern of set values of heater power in a straight body forming process in the next pulling is calculated such that the set values of heater power is given feedback on pattern correction value W of heater power determined by the following equation:
W=Ws?(Ha?Hb)wherein, W represents the pattern correction value of heater power, Ws represents a heater power value at the start of the straight body forming process, Ha represents a removed heat quantity at the start of the straight body forming process, and Hb represents the calculated value of the removed heat quantity in the straight body forming process.