A regression equation generation unit (3) performs base decomposition on spectral information for calibration curve preparation determined by the temperature value of an object being measured which is measured by using a contact-type thermometer, calculates a base score a(k,j), and calculates a multiple regression coefficient (c(k), k=1,2) from the score a(k,j) and the temperature of the temperature indicator value of the contact-type thermometer (30) corresponding to the spectral information for calibration curve preparation. A temperature estimation unit (4) calculates the score a(k,j) based on the spectral information of the object being measured and the base calculated by the regression equation generation unit (3), and estimates the temperature of the object being measured based on the calculated score a(k,j) and the multiple regression coefficient (c(k), k=1, 2). Therefore, the temperature of the object being measured can be precisely measured without having to calculate a combined solution for emissivity and without any effect from fluctuations in emissivity.