1. A projector apparatus comprising: a projection unit which projects an image corresponding to an input image signal; an instruction unit which issues an instruction for performing keystone correction; a distance survey unit which surveys a distance between the projector apparatus and each of a plurality of positions on the image projected by the projection unit, in accordance with an instruction from the instruction unit; a keystone correction unit which performs keystone correction of the image projected by the projection unit, in a manner that the image becomes a rectangle having an appropriate aspect ratio based on distances obtained by the distance survey unit; and a focus control unit which brings the image projected by the projection image into focus, at a center position of the image after being keystone-corrected by the keystone correction unit.