To provide a contour detection processing circuit by which the contour part of a picture is correctly detected concerning the picture with the influence of noise, etc.

The circuit is provided with detection processing means 11, 12, 13, 14 and 15 for performing the detection processing of the contour part concerning the continuous picture area signals of an input picture signal. The circuit is also provided with a pattern comparing means 21 for adopting detection processing data of a desired pixel as reference through the use of detection processing data of the means 11, 12, 13, 14 and 15 so as to generate an arrayal pattern where detection processing data of the prescribed number of pixels being adjacent to the pixel are made into block and comparing the arrayal pattern with a previously prepared reference pattern being the reference pattern of a data block which is the same as the arrayal pattern in size so as to judge the coincidence/non-coincidence of them. The circuit is also provided with a data converting means 31 for converting the arrayal pattern into a pattern being different from the arrayal pattern based on the reference pattern when the arrayal pattern coincides with the reference pattern by the result of comparison in the pattern comparing means 24 so as to output it and outputting the arrayal pattern as it is unless the arrayal pattern coincides with the reference pattern by the result of comparison in the pattern comparing means 21.