PURPOSE: To ensure the judgment of the degree of deterioration of dewatering fluorocarbon in a short time by providing a microwave generating device at the upper part of a measuring container, and providing an electronic measuring device at the lower part of the container.

CONSTITUTION: A beaker 15 containing dewatering fluorocarbon liquid 13 as a sample is mounted on an electronic measuring device 7 which is provided at the lower part in a measuring container 3. The water molecules of the dewatering fluorocarbon liquid 13 in the beaker 15 are excited and boiled by a microwave generating device 11 which is provided at the upper part of the measuring container 3. The fluorocarbon whose boiling point is lower than that of water is gasified and evaporated in a short time. Only dewatering activator whose boiling point is 100°C or higher remains in the beaker 15. The weight of the remaining activator is measured with the electronic measuring device 7. The actually measured value is inputted into an operating means 17. In the operating means 17, the actually measured value is compared with a reference value which is inputted beforehand, and the degree of deterioration of the sample 3 is judged.