Radiation thermometer and thermometry method

A radiation thermometer, comprising:

• a broadband light source configured to generate broadband light to be irradiated to a measuring target object;
• an optical filter configured to, when the broadband light generated by the broadband light source is incident on the measuring target object, pass only light in a predetermined wavelength range of reflected light reflected by the measuring target object and heat radiation light radiated from the measuring target object;
• a light receiver configured to receive the light in the predetermined wavelength range which passed through the optical filter;
• and
• a calculator configured to calculate a temperature of the measuring target object by using reflected light intensity and heat radiation intensity of the light in the predetermined wavelength range received by the light receiver,
• wherein an emission spectrum of the broadband light is a spectrum with a full width at half maximum which is equal to or wider than the predetermined wavelength range, and with light intensity increasing while a wavelength thereof becomes longer in the predetermined wavelength range.