The (129)I-Mossbauer spectroscopy was applied to iodine-doped single-walled carbon nanotubes and a comparison between nanotubes with open-ends and closed-ends was discussed. The iodine doping was done in a gas phase at a lightly-doped region, where the iodine exists in the forms of triiodides (I(3)(-)) and monoiodides (I(-)). No significant difference between the iodine in open- and closed-end nanotubes was found. This fact implies the gas-phase lightly-doped iodine exists mostly at the inter-tube site in the bundle of the tubes and hardly exists inside the tubes.