1. A remote instruction system comprising a control portion, the control portion transmitting an image captured by an image capturing portion provided for capturing the image of a subject to a remote terminal, and controlling a projection portion to project an annotation image onto the subject according to an instruction issued from the remote terminal on the basis of the image captured, the control portion measuring a reflection characteristic of a surface of the subject on the basis of the image captured, and converting a color of the annotation image to be projected onto the subject on the basis of a comparison result between the color of the annotation image instructed by the remote terminal and the reflection characteristic of the surface of the subject to project the annotation image onto the subject.