An image processing device for a projector including an image formation section that emits light of an image, and a projection system that projects the emitted light onto a projection surface. The image processing device has a distortion correction technique for images displayed on the projection surface. The image processing device has a target display area determination section that determines, in a display area serving as a reference on the projection surface, based on a current value of a parameter, any of target display areas set for values possibly taken by the parameter within an allowable range to be targeted on a distortion-free image for display on the projection surface; a reference formation area determination section that determines a reference formation area to be formed with a virtual distorted image and a correction application section that generates corrected image data for supply to the image formation section.