1. A remote instruction system comprising an annotation forming portion that: overlay-displays an image of a target taken by an image taking portion, in a display area of application software; displays an edited image in the display area by use of the application software; extracts the edited image displayed according to a difference between displayed images prior to and subsequent to a generation of the edited image; and forms an annotation image from the edited image extracted to project the annotation image onto an image-taken area of the image taking portion by a projecting portion according to an instruction given on the basis of a taken image.