This paper describes the efficient measuring method of 3-D edge profile with high accuracy for free form surface including die and mould model shapes. We propose a new method of the 3-D edge profile measurement technique by means of optical ring image sensor. The two-step measurement strategy for measuring the edge profile is proposed. In the first step, the edge area for re-measuring is extracted by rough measurement and the measuring path of the sensor is decided. In the second step, the edge positions are estimated, namely the edge profile is measured by fine measurement along the measuring sensor paths. Measurement results of hole edge on a cylindrical surface show the validity of out method.