To provide a silver film coating composition that substantially generating no decomposition product with heat and/or light, and provide a light reflector and an illuminator having the same.

The light reflector 1 comprises the base material 2, the undercoating layer 3 formed on the surface of the base material 2, the light-reflecting layer 4 that is formed with Ag or Ag base alloy on the undercoat layer 3 and the top coat layer 5 formed so as to cover the light reflecting layer 4. The undercoat layer 3 and the top coat layer 5 include a straight silicone resin as a coating film base component, wherein the straight silicone resin component has a weight-average molecular weight of more than 3,000, further the degree of cross-linking in the siloxane linkage is 1 to 1.4 average organic group connecting to one silicone atom.