1. A remote instruction system comprising at least one image recorder and at least one image projector, the number of the image recorders plus the number of image projectors being three in total, the image recorder recording an image of at least a portion of a target region, the image projector projecting an annotation image on at least a portion of the target region, wherein the number of regions is respectively assigned within the target region to the image recorder and the image projector, according to the number of the image recorders and that of the image projectors.