In a mirror system to enable projection of an observer of the invention, a whole image at rear side of the observer can be easily seen. The mirror is provided with a first mirror (1), a second mirror (2), a third mirror (3), a fourth mirror (4), and a base (5) to support the four mirrors integrally.
The four mirrors stand contiguous to each other in sequence, and mirror surfaces of the contiguous mirrors are perpendicular to each other and mirror surfaces of every other contiguous mirror are arranged in opposition, so that the incident ray to the first mirror at the horizontal incident angle 45° is projected through the second mirror and the third mirror onto the fourth mirror. When the observer (H) backs against the first mirror and faces the fourth mirror at intermediate position between the first mirror and the fourth mirror, a whole image at rear side of the observer in the same direction as that of the observer can be projected onto the mirror (4) in front of the observer.