A carbon fiber bundle that satisfies retaining a twist count of 2 turns/m or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 μm or more and a heat loss rate at 450° C. of 0.15% or less, and formula (1) wherein Lc is crystallite size and π002 is an orientation parameter of crystallites determined from bulk measurement of the entire fiber bundle: π002>4.0×Lc+73.2 (1); and a carbon fiber bundle that satisfies: retaining a surface layer twist angle of 0.2° or more when suspended with one end fixed and the other end free; having a single fiber diameter of 6.1 μm or more and a heat loss rate at 450° C. of 0.15% or less, and formula (1).