To provide a film thickness measuring apparatus and a film thickness measuring method, capable of precisely measuring a distribution of film thickness of a coated layer formed on a surface of an object, and to provide a surface temperature inspecting apparatus and a surface temperature inspecting method, capable of precisely measuring a distribution of surface temperature of the object having the coated layer formed on its surface, regardless of the distribution of film thickness of the coated layer.

The distribution of film thickness of the coated layer 11 formed on a cavity surface 10a of a forging die 10 is calculated based on a difference value between measured temperature distributions derived from intensity distributions of two kinds of infrared radiation having different wavelength bands. Furthermore, an emissivity distribution of the cavity surface 10a of the forging die 10 is compensated based on the thickness of the coated layer 11, and the distribution of surface temperature of the forging die 10 is calculated based on the compensated emissivity distribution of the cavity surface 10a of the forging die 10 and intensity distributions of three kinds of infrared radiation having different wavelength bands.