PURPOSE: To obtain a metal mirror having high reflectance which does not deteriorate with the lapse of time.

CONSTITUTION: This mirror is produced by forming a SiO base layer 2 on the surface of a substrate 1 and further forming a first Cr film 3, an Ag reflection film 4, a second Cr film 5 and a protective layer 6 compopsed of an Al2O3 film 6a and a SiO2 film 6b. The first Cr film 3 increase the adhesion property between the under coating layer 2 and the reflection film 4 and is effective to form the reflection film 4 having no defect. The second Cr film 5 has an effect to smoothen the surface of the reflection film 4 and to make the film of the protective layer 6 dense.