data vb expressed by the equation 1 in this case va and vb coincide so that it proceeds to the next step 75 in the step 75 the error recognition and the error representation are invalidated which are recognized by the design error recognition portion 41 with respect to the contact hole region i e the region 15 that is as a result of the comparison process in the steps 73 and 74 it is determined that the feature of the figure of the contact hole region 15 shown in fig4 a coincide with the feature of the fig2 shown in fig5 it is recognized that the contact hole region 15 need not be treated as a design error accordingly the error recognition of the contact hole region 15 is invalidated in the step 75 in a step 76 it is determined if the above mentioned process has been completed with respect to the all contact hole regions recognized as a design error by the design error recognition portion 41 when the above mentioned process with respect to the all contact hole regions is completed the process in the recognition invalidation portion 42 is finished if the contact hole regions to be processed are still left or no coincidence is detected in the steps 73 and 74 it returns to the step 72 and the same process as the above mentioned is conducted with respect to one of other contact hole regions fig6 shows the process in the step 74 more specifically vector data va and vector data vb are compared with each other for each corresponding item when there is a coincidence for all pairs compared it is determined that va vb however in the case.