Model test of the Near Surface Disconnecable Drilling Riser (NSDDR) which has an air can system near the top for making free-standing condition was conducted by use of a riser model corresponding to 750m length in fullscale. Purpose of the test is to grasp the characteristics of NSDDR in irregular waves with constant current. In the test, we observed remarkably riser's horizontal motions due to vortex induced vibration (VIV), and found that the bending moment variation induced by VIV is the same order as the variation induced to the flow direction of the riser. In the drilling mode, bending moment variation of NSDDR is partially about 25% larger than that of the conventional riser without air can. Bending moment variation in free-standing mode is about 20% of that in hang-off mode at the same significant wave height except the riser bottom. At the riser bottom, both static and significant values of the bending moment become largest, so we should pay attention to the strength.