The objectives of present paper are to investigate the properties of second-order sum-frequency wave exciting forces on column-footing type floating bodies and to confirm the existence of wave periods where the second-order wave exciting forces in vertical direction become very small. The second-order sum-frequency wave exciting forces are obtained from the linear velocity potentials and the radiation potentials of sum-frequency utilizing the extended Haskind formula. The linear and the radiation potentials are computed by the hybrid boundary element method. The vertical second-order sum-frequency wave exciting forces on column-footing type floating bodies are computed systematically and the numerical resalts are compared with the experimental resalts, so that those properties are made clear. Further, the existence of periods where the vertical exciting forces become very small are discussed.