The temperature measuring system using optical interference includes a light source which generates measuring light; a spectroscope which measures an interference intensity distribution that is an intensity distribution of reflected light; optical transfer mechanisms which emit light reflected from a surface and a rear surface of the object to be measured to the spectroscope; an optical path length calculation unit which calculates an optical path length by performing Fourier transformation; and a temperature calculation unit which calculates a temperature of the object to be measured on the basis of a relation between optical path lengths and temperatures. The light source has a half-width at half-maximum of a light source spectrum that satisfies conditions based on a wavelength span of the spectroscope. The spectroscope measures the intensity distribution by using the number of samplings that satisfies conditions based on the wavelength span and a maximum measurable thickness.