The analysis of aerodynamic noise radiation from a circular cutting tool with a columnar tooth model is made. Particularly, this experiment deals with a circular cutting tool with a tooth length of 14.3% to 47.6% of tool diameter. Correlations between aerodynamic noise and the flow of neighboring tooth model that is a noise source are clarified. From the experimental results, an aerodynamic noise spectrum at farfield agrees with spectrum distribution of the vortex that was generated behind a columnar tooth model, and a principal noise source distributed at an appointed end of the tooth. A spectrum distribution behind a tooth model that is calculated by a tangential velocity of flow on the tooth model and a velocity of inflow to the tooth model agrees with experimental results.