1. An image adjuster that adjusts a projection image of a projector, the projector comprising a light source, an electric optical device that modulates the light beam irradiated by the light source in accordance with image information and a projection optical system that enlarges and projects the light beam modulated by the electric optical device, the image adjuster comprising: a projection surface onto which the projection image of the projector is projected; a reference tone image generator that generates a plurality of reference tone images on the projection surface as an adjustment reference; an image signal input means that inputs an image signal including a tone signal corresponding to the plurality of reference tone images, the image signal simultaneously displaying a plurality of tone images on the projector to be adjusted; an image importing device that simultaneously imports the plurality of reference tone images and the plurality of tone images projected by the projector as image data; an image processor that conducts image-processing of the image data imported by the image importing device; and a correction data generator that generates image display correction data of the projector based on the result of the image-processing by the image processor.