Abstract: Radiation wave surrounding a horizontally submerged truncated circular cylinder with harmonic sway motion is analyzed using the linear potential wave theory. Using the method of separation of variables, harmonic expressions of the velocity potential in terms of the unknown constants are obtained in three subregions of the domain occupied by the water. A simple matching technique is used to satisfy the continuity of pressures and normal velocities at the common boundary of the subregions. The velocity potential is thus obtained, and consequently, the hydrodynamic force on the side of the cylinder expressed as a function of equivalent added mass and damping is determined. The solution presented not only is able to consider the gravity wave on the water surface, but also can be applied to truncated circular cylinder submerged in the arbitrary depth of water. Results of examples illustrated the accuracy of the solution and showed that using coefficient of hydrodynamic added mass in Morison equation would over-evaluate the hydrodynamic force on the side of the cylinder.