PURPOSE: To judge automatically whether a water content measuring circuit is normal or not during measurement by changing over and using an equivalent resistance parallel to a resistance of a measuring electrode part and outputting an abnormal signal.

CONSTITUTION: An electrode 1 at the electrode part of a moisture meter for measuring the moisture content of cereals, etc. and the equivalent resistance 3 of moisture content parallel thereto are selected through a switch 4 changed over periodically. If the moisture content due to the resistance 3 is different from a prefetermined normal moisture content, the abnormality is alarmed through a CPU, a judgment can be made automatically during measurement as to whether the moisture content measuring circuit is normal or not, and the occurrence of erroneous measurement is prevented.