The added resistance acting on a circular cylinder with low forward speed in regular waves are provided numerically and experimentally. The velocity potential is calculated by making use of the source distribution method which is considered not only the singularity distribution over the hull but also a line singularity distribution. And in order to investigate the effect of the forward speed, it is also shown a few approximate numerical methods in which it is assumed that the forward speed is very small. These calculations are made for a circular cylinder and the results are compared with the experimental ones. It is observed that the calculated values are in fairly good agreement with those of experiments.