Some flow visualization experiments and measurements of surface pressure, Strouhal number, etc. around a finite circular cylinder on a flat plate have been performed in order to study the effect of a three-dimensional flow. The slenderness parameter of the cylinder is in a range of l/d=1∼8, where the slenderness parameter influences remarkably the flow behavior. From an analysis of mean and periodical motion in the near-wake flow, the following results are obtained. (1) The separation velocity at the side wall is lower than that of a two-dimensional cylinder, and this decreases the drag coefficients. (2) A pair of trailing vortices exist right below the free-end. (3) Down-wash flow and the trailing vortex near the free-end dominate the behavior of Karman vortex shedding. Finally, based on these results, the flow models around the finite height cylinder are presented.