Abstract: Disclosed herein is a measuring apparatus and a measuring method which can measure a physical property value such as an oxygen content or thermal conductivity of a sample material such as an aluminum nitride sintered body with high accuracy, over the entire material in a short time. A microwave oscillation source generates microwaves. A sample material to be evaluated, such as an aluminum nitride sintered body, is placed in a cavity resonator, irradiated with microwaves (M), and subjected to a magnetic field (H) applied by electromagnets. An amount of microwaves absorbed by the object is measured by a microwave absorption measuring unit. This amount of microwave absorption is obtained from an electron spin resonance spectrum. The concentration of unpaired electrons in the object is obtained from the measured amount of microwave absorption on the basis of a known relation between an amount of microwave absorption and concentration of unpaired electrons.