Abstract: A voltage signal associated with the moisture content of a sample in grain or sand form is converted into a digital signal value by an analog-to-digital converter. A programmable read-only memory capable of erasure and field rewriting has stored therein conditions for computation and calibration parameters associated with various types of the sample. Upon designation of one of the types, the conditions for computation for the designated type of sample are picked up, and a moisture content is computed and digitally indicated by use of the computation parameters for the designated sample type. This moisture content value can be compensated for temperature, and the conditions for computation and the calibration parameters in EPROM are capable of being erased or rewritten.