In the present study, we deal with one of the most fundamental and common topics related with the ground effect: that is, a sliding flat plate (or thin aerowing) just above the stationary ground surface. Specifically speaking, by using a moving-belt system, we investigate the ground effect in such a simple model. Namely, we put a two-dimensional thin flat plate above the belt in a wind-tunnel test section, and conduct flow visualizations with particle-image-velocimetry PIV analyses, together with flow-velocity measurements using a hot-wire anemometer HWA. As a result, we have shown the influence of the gap between the flat plate and the moving wall. Furthermore, we have confirmed that, the antisymmetric alternating vortex street past the flat plate tends to be broken and weakened, due to the existence of the moving wall below the flat plate, if the gap becomes less than a critical value.