(57) The present invention relates to a process for producing pitch for use in production of carbon fiber which comprises subjecting a pitch starting material to a first stage heat treatment at a temperature of 380 to 500°C under a pressure of 1 to 1,500 mmHg and then to a second stage heat treatment at a temperature of 450 to 550°C under a pressure of 0.1 to 20 mmHg, wherein the pitch starting material has a number average molecular weight of 300 to 500, weight average molecular weight/number average molecular weight of 1.5/1 to 2.2/1, a boiling point of at least 450°C, a residue content as determined by heating up to 800°C in nitrogen gas at a rate of 10°C per minute of not more than 5% by weight, and a peak area at the starting point as determined by developing on a silica gel thin layer with a mixed solvent of 95% by volume of dichloromethane and 5% by volume of methyl alcohol of not more than 1%.
The present invention further relates to novel pitch for use in production of carbon fibers as obtained by the above process and a process for producing carbon fibers using said pitch. According to the present invention, the pitch capable of providing carbon fibers having a high tensile strength and a high knot strength can be obtained.