To provide a magnification variable mirror which is lightweight, allows conversion between a planar mirror and a concave mirror to be easily carried out, has a structure less liable to be damaged, and can be incorporated into another apparatus and used, and an apparatus incorporated with the magnification variable mirror.

A magnification variable mirror has a film-like mirror 3 formed by vapor deposition of silver or aluminum on a resin film and mounted in a circular mirror frame 2, and an airtight space V can be formed between the film-like mirror 3 and a transparent window 4 mounted in the mirror frame 2 with a clearance left from the film-like mirror 3. The magnification variable mirror is furthermore equipped with: a system having a pump 7 connected with the airtight space V via a flow channel and a release valve C capable of appropriately breaking the air tightness of the airtight space V, increasing the air pressure inside the airtight space V by manually or electrically driving the pump 7 to recess the film-like mirror 3 to make a concave mirror, and returning the film-like mirror 3 to a planar mirror by the release valve C.