1. A projector comprising: a projecting section projecting a whole image including an individual image and having a function of adjusting the size of the whole image, the whole image being configured to be projected on a screen; an image taking section taking an image of the screen; an updating section detecting a position change instruction based on the image taken by the image taking section, and updating position data which shows a position of the individual image according to the position change instruction; and a control section performing control so as to make the projecting section adjust the size of the projected whole image according to the position data in a state in which the whole image includes a whole of the individual image, wherein the control section determines whether or not the individual image moves out of the whole image according to the position data and enlarges the size of the whole image when the individual image moves out of the whole image.