Provided is a method of calculating a temperature distribution with higher accuracy than a conventional method, which calculates a temperature distribution of an inner surface of a silica powder molded body during manufacturing based on boundary conditions corrected in accordance with the actually measured temperature in consideration of plasma radiation by arc discharge and heat radiation of arc discharge.According to a method of calculating a temperature distribution of a crucible during manufacturing, includes a temperature calculation process in which a temperature calculator calculates temperature distribution in an inner surface of a silica powder molded body through a numerical calculation method which mesh-divides an object to be calculated, by calculating heat flux from heat plasma modeled by a gas flow and radiation of heat plasma radiated from arc electrodes, wherein the temperature distribution is calculated by adjusting gas flow and radiation conditions in a way that the calculated temperature distribution and the actually measured temperature distribution of an inner surface of a silica powder molded body becomes similar, and reading, from a correspondence table, gas flow and radiation conditions corresponding each step of a control sequence for producing a crucible.