To provide a bevel position detecting method capable of detecting a bevel at high speed by using an image signal of a television camera.

At first, a gray level image in the vicinity of a bevel before profile controlling is stored in a memory and a prescribed region thereof is set as a teaching pattern. A region of which size is equal to that of the teaching pattern is sequentially taken out from the gray level image in the vicinity of the bevel during the profile controlling is set as an input pattern. Next, a position of the bevel is determined based on a position of the input pattern wherein a difference of pixel data between the corresponding teaching pattern and input pattern is within a range of predetermined agreement judgment value and the number of pixels thereof is the largest.