PURPOSE: To perform the analysis of synthetic rubber within a short time with good accuracy, by automatically changing over the atmosphere of a heating apparatus from an inert gaseous atmosphere to an active gaseous atmosphere at predetermined temp. and correcting a componential ratio by using correction coefficient.

CONSTITUTION: A heating apparatus 1 is filled with a synthetic rubber specimen being a measuring object. An atmosphere control apparatus 2 is operated to convert the atmosphere around the specimen to an inert gaseous atmosphere to heat the specimen at a temp. rising speed of 50°C/min and the thermal change in the wt. of the specimen is measured by a wt. measuring apparatus 3. The temp. of the specimen is raised while the state change such as transformation or reaction of the specimen is detected by a detection apparatus 8 and, at the point of time of specimen temp. of 800°C, the atmosphere around the specimen is changed over to an active gaseous atmosphere. Further, the temp. of the specimen is raised to about 1,000°C to generate the decompositional combustion reaction of carbon black. The measured results obtained by the wt. measuring apparatus 3 and the detection apparatus 8 are introduced into an analyser 6 and operational correction is performed by using correction coefficient and the corrected values are recorded on a recording apparatus 7.