A stripe shaped standing wave appears on the surface of liquid film flowing around a horizontal circular cylinder. The wave grows in the downward direction under the influence of centrifugal force. The amplification was theoretically investigated from the momentum equation on the wave peak. The results agree with those measured experimentally for three kinds of test liquids. The amplification ratio A is mainly dependent on a parameter Fr₀•R/δ₀ concerning gravitational and centrifugal forces, and slightly on the Reynolds number.