Disclosed is a picture quality evaluation system. The system calculates the difference between data that represent a feature value of a pixel set that constitutes a first image and data that represent a feature value of a pixel set that constitutes a second image. The system then uses at least the first image or the second image to determine the main area of focus of an image that has a specific feature and then calculates the main area of focus. The system then weights the difference in the feature value in the pixel set contained in the main area of focus and calculates the picture quality value of the first image, based on the weighted difference.