1. A rotary indicating device which comprises a base member adapted to be rotated about a rotary axis and having an indication surface, said indication surface including an indication region formed thereon and representing a desired image, said indication region comprising a plurality of image element units each of which includes a predetermined number of image elements each consisting of a corresponding reflection face, said reflection face of each image element unit being inclined in various directions at a same angle with respect to a standard plane perpendicular to a rotary axis of said base member so that when said base member rotates, said reflection faces of each image element unit alternately reflect light coming at an angle with respect to said rotary axis, into a fixed direction at a fixed rotary position of said base member.