PURPOSE: To provide an automatic discrimination device for a section having enough discrimination accuracy and capable of realizing an automatic processing line at a low cost.

CONSTITUTION: When a section 1 on a conveyance device 2 passes through a position, a passing sensor outputs a passing signal. A data processing circuit 4 instructs a color sensor 5, an image-pickup element 6 and a length- measurement device 8 to measure the section 1. The image-pickup element 6 takes a cross section of the section 1 so that an image-processing circuit 7 abstracts a characteristic value of the cross sectional shape on the basis of the image data from the image-pickup element 6. The color sensor 5 measures a tone of color of the section 1. The length-measurement device 8 measures a length of the section 1. The data processing circuit 7 collates the characteristic value of the cross sectional shape of the section from the image-processing circuit, the value of the tone of color from the color sensor 5 and the measured value from the length-measurement device with pre-registered data to discriminate the section 1. The discrimination result is outputted to a control device or the like in a cutting apparatus.