To provide a film mirror which is lightweight and flexible, excellent in weather resistance, does not cause degrading in regular reflectance and peeling of the film at the time of cleaning even after long period of outdoor installation, and has favorable regular reflectance to the sunlight, to provide a method for manufacturing the film mirror, and to provide a reflection device for solar heat power generation.

Film mirrors (10a and 10b) are formed by providing a silver reflection layer 3 on a film base material (first resin base material 1). A method for manufacturing the film mirrors (10a and 10b)comprises the steps of: making a reducing agent to be contained in at least one of a base resin layer 2 on which the silver reflection layer 3 is formed, and a coating liquid containing a silver complex compound, and applying the coating liquid to the base resin layer 2 to form a coated film; and heating and calcining the coated film to form a silver reflection layer 3.