Graphite film and method for producing graphite film

A method for producing a graphite film, comprising:

• a sag controlling step of controlling (i) temperatures of a polymer film at both widthwise ends and (ii) a temperature of the polymer film in a widthwise middle portion within a temperature range from a starting temperature of thermal decomposition of the polymer film to a sag controlling temperature of the polymer film;
• and
• a step of treating the film obtained in the sag controlling step with heat at a temperature of 2000° C. or higher after the sag controlling step,
• wherein the sag controlling step comprises treating the polymer film with heat so that the temperatures (i) are higher than the temperature (ii) within the temperature range from the starting temperature of thermal decomposition of the polymer film to the sag controlling temperature of the polymer film and so that a temperature gradient over an area extending from the both widthwise ends of the polymer film toward the widthwise middle portion of the polymer film is not less than 2.5° C./m, and
• the film obtained in the sag controlling step is treated with heat at a temperature of 2000° C. or higher after the sag controlling step, and
• wherein the sag controlling step treats the polymer film with heat under a condition that the temperature gradient over an area extending from the both widthwise ends of the polymer film toward the widthwise middle portion of the polymer film is not less than 2.5° C./m and not more than 100° C./m.