Water dispersible carbon fibers, (1) wherein the surface oxygen concentration (O/C) of each of the single fibers is 0.03 or more and less than 0.12 as measured by X-ray photoelectron spectroscopy and forming a first contact angle with water of 75° or less as measured by the Wilhelmy method; (2) wherein the O/C is 0.12 or more and less than 0.20 and forming a first contact angle with water of 65° or less as measured by the Wilhelmy method; or (3) wherein the O/C is 0.20 or more and 0.30 or less and forming a first contact angle with water of 55° or less as measured by the Wilhelmy method; and wherein a sizing agent containing a surfactant as a major component has adhered to the single fibers of each of the water dispersible carbon fibers.