An instruction system including: a capture device; a projection device; a control device including: a judgment portion that judges visibility of an annotation image; a specifying portion that specifies a projection mode of the annotation image from projection modes of the annotation image stored into a storage portion, based on a result of the judgment; a notification portion that notifies the projection mode specified by the specifying portion; and a projection control portion that causes the projection device to project the annotation image corresponding to an instruction on the basis of the projection mode notified from the notification portion; and a terminal including: a reception portion receiving the captured image, and the projection mode notified from the notification portion; and a transmission portion transmitting the instruction on the basis of the received captured image, and the instruction on the basis of the notified projection mode, to the control device.