condition comprising a ratio of solvent to oil of 10 1 a temperature of 180 u00b0 c and a pressure of 40 kgf cm 2 the resulting extraction component was subjected to thermal modification at a temperature of 410 u00b0 c for 10 hours to obtain a pitch used as a raw material for carbon fibers properties of the heavy residual oil from middle east crude oil a used as a raw material those of the solvent extraction component and those of the pitch used as a raw material for carbon fibers are shown in table 1 further carbon fibers which were obtained by melt spinning of the above described pitch used as a raw material for carbon fibers at 360 u00b0 c infusiblizing at 260 u00b0 c in the air and carbonizing at 1 000 u00b0 c had a tensile strength of 11 tons cm 2 and a modulus of elasticity of 1 000 tons cm 2 when the fibers prepared by carbonizing at 1 000 u00b0 c were additionally graphitized at 1 800 u00b0 c they had a tensile strength of 15 tons cm 2 and a modulus of elasticity of 2 100 tons cm 2 after a heavy residual oil having a boiling point of more than 350 u00b0 c prepared by distillation of middle east crude oil b was subjected to hydrogenation treatment under a condition comprising a temperature of 390 u00b0 c a pressure of 160 kgf cm 2 a liquid space velocity of 0 5 hr 1 and a ratio of hydrogen oil of 1 000 nm 3 kl a fraction having a boiling point of.