Process for producing graphite film

A method for producing a graphite film by heat-treating a polymer film, comprising:

• a film modification step for performing heat treatment at a heating rate of 5° C./min or more in a temperature range from (i) a lower limit to temperature rise being equal to or higher than a starting temperature of thermal decomposition of the polymer film to (ii) an upper limit to temperature rise being equal to or lower than an intermediate temperature of thermal decomposition of the polymer film while continuously feeding a long polymer film into a heat treatment apparatus, the polymer film having a birefringence of less than 0.13and the upper limit to temperature rise being 605° C. or lower;
• following the film modification step, performing cooling at a cooling rate of 10° C./min or more in a temperature range from (i) the upper limit to temperature rise to (ii) a temperature being equal to or lower than the starting temperature of thermal decomposition of the polymer film;
• and thereafter
• performing heat treatment at a temperature of 2000° C. or higher.