PATTERN INSPECTION APPARATUS AND PATTERN INSPECTION METHOD

A pattern inspection apparatus includes a design pattern image generation circuit to generate a first design pattern image by developing an image of the first design pattern, and a second design pattern image by developing an image of the second design pattern for assisting the first design pattern, a comparison circuit to detect a defect candidate by comparing, for each pixel, the measured image with a main reference image which is a predetermined one of the first design pattern image and the second design pattern image, and a determination circuit to determine whether the defect candidate is a defect by using determination conditions obtained using, as a sub reference image, another predetermined one of the first design pattern image and the second design pattern image.