An object of the invention is to calibrate an upper pyrometer for indirectly measuring a substrate temperature at the time of epitaxial growth in a comparatively short time and with accuracy to thereby improve the quality of an epitaxial substrate.After calibrating an upper pyrometer by a thermocouple mounted to a temperature calibrating susceptor, a measured value of a lower pyrometer is adjusted to a calibrated value of the upper pyrometer. Then, a correlation line between substrate temperature indirectly measured by the upper pyrometer at the time of epitaxial growth onto a sample substrate and haze of a sample substrate measured immediately after epitaxial growth is set to indirectly measure a substrate temperature by the upper pyrometer at the time of epitaxial growth onto a mass-production substrate. Moreover, substrate temperature at the time of epitaxial growth onto the mass-production substrate is estimated by applying the haze of the mass-production substrate measured immediately after epitaxial growth to the correlation line and then a measured temperature of the upper pyrometer is adjusted to the estimated temperature.