Abstract: A real-time PCR system for detecting gene expression levels includes plural reaction regions, a like plural number of heating portions arranged corresponding to the reaction regions and having heat sources, respectively, an optical unit capable of irradiating exciting light of a specific wavelength to all of the plural reaction regions, and a like plural number of fluorescence detecting portions arranged corresponding to the reaction regions, respectively. The heating portions are each provided with a temperature detector for detecting a temperature in a vicinity of the corresponding heat source and converting the temperature into an electrical signal and also with a controller for controlling a thermal dose from the corresponding heat source based on a correlation between electrical signals and calorific values of the heat source stored beforehand.