PURPOSE: To accurately detect inclination and position of a pattern of cloth even in cloth having a striped pattern with approximately the same lightness and plural colors and not to prolong a detection time.

CONSTITUTION: At least part of a pattern of plural colors of roughly cut cloth having the pattern is pictured by a color camera 4. At first, signal lines of R, G and B corresponding to the three primary colors outputted from the color camera 4 are changed by a switch circuit 5. Each picture image signal outputted at every change is successively made into a quantum, memorized in an image picture memory 7 and its projection is taken. An image signal optimum for detection of the pattern is selected from each result of the projection. Then while the same pattern is detected, projection is taken only on the selected one image picture signal outputted from the color camera to detect inclination of position of the pattern.