A thick delta wing with a rounded leading egde has been experimentally studied. To understand the basic flow field of such a wing, experiments have been conducted in low speed wind tunnel at Nagoya university. Three types of flow visualization: oil flow, smoke wire, and tuft methods are employed, and forces: lift and drag, and pressure distributions were also obtained. The same test has been conducted for a thin delta wing for comparison.The results show the different flow field of the thick delta wing from those commonly known for delta wings. However, in other properties except for the flow pattern, similarities were observed between the thick delta wing and thin delta wing.