An accurate determination of neutron total cross section of carbon has been made by the transmission method in the energy region 3 keV to 660 keV. No structure is observed in the total cross section over the whole energy region, and it is concluded that the upper limit of the width of the proposed level at 610 keV neutron energy must be 10 eV in order to escape detection in the present experiment. The observed total cross section has been analysed in terms of the effective range theory as well as the resonance theory, and the results are found to be in good agreement. The relative reduced width for the bound level at -1.86 MeV (i.e. the 3.09 MeV 2s 1 2 state in C13) is found to be θ2 = 0.2, and the interaction radius is found to be 4.7 fm.