The velocity profile of particles in a moving bed was directly measured by means of a Bore Scope connected with a video system. The image of a colored tracer particle inside the flowing layer was taken and recorded with a video camera and recorder through the scope. It was inserted horizontally inside a guide tube and the top end was located on the vertical plane through the axis of a conical vessel. Thus, the particle velocity at constant radius from the apex or at constant inclination angle from the axis could be obtained throughout the vessel. As a result, the particle velocity distribution was satisfactorily expressed by a mathematical model in polar coordinates. It is written by a dimensionless equation on the basis of the central velocity along the axis and a half of the cone angle.