There is provided a conductive fiber containing a conductive substance, and having stable conductive performance with a small variation in its conductive performance. A conductive fiber contains carbon black as a main conductive component in a fiber-forming polymer, wherein the carbon black is composed of a mixture of at least two kinds of the following carbon blacks (A) and (B), which is obtained by mixing them at an A/B ratio (by weight) of 90/10 to 10/90: (A) a conductive carbon black having an average particle size of 20 to 70 nm and an oil absorption defined in JIS K 5101 of 100 to 600 ml/100g; and (B) a conductive carbon black in which the average article size ratio thereof to said conductive carbon black (A) is from 1.1 to 3, and the oil absorption ratio thereof to said conductive carbon black (A) is from 0.9 to 0.2.