A moisture meter comprising: a mass measurement unit configured to measure a mass of a specimen placed on a weighing dish; a heating unit configured to heat the specimen; a control arithmetic unit configured to control the heating unit to heat the specimen until a change in mass of the specimen becomes not more than a predetermined threshold and calculate a moisture content of the specimen from the change in the mass of the specimen before and after heating; and a storage unit, wherein the control arithmetic unit includes a standard substance measurement unit configured to execute a measurement of a moisture content a plurality of times by using, as the specimen, a standard substance for inspection having a predetermined theoretical moisture content with an arbitrary mass when being heated at a predetermined temperature, and a standard deviation calculation unit configured to calculate a standard deviation of a measured moisture content in the measurement executed the plurality of times, characterized in that the control arithmetic unit includes an average moisture content calculation unit configured to calculate an average moisture content by averaging measured moisture content in the measurement executed the plurality of times, and wherein the control arithmetic unit includes a state diagnosis unit configured to evaluate the presence or absence of an abnormality in the mass measurement unit by comparing the average moisture content with the theoretical moisture content of the standard substance stored in the storage unit, and wherein the control arithmetic unit is further configured to evaluate an influence of an installation environment by determining whether the standard deviation is not more than a predetermined value. a mass measurement unit configured to measure a mass of a specimen placed on a weighing dish; a heating unit configured to heat the specimen; a control arithmetic unit configured to control the heating unit to heat the specimen until a change in mass of the specimen becomes not more than a predetermined threshold and calculate a moisture content of the specimen from the change in the mass of the specimen before and after heating; and a storage unit, wherein the control arithmetic unit includes a standard substance measurement unit configured to execute a measurement of a moisture content a plurality of times by using, as the specimen, a standard substance for inspection having a predetermined theoretical moisture content with an arbitrary mass when being heated at a predetermined temperature, and a standard deviation calculation unit configured to calculate a standard deviation of a measured moisture content in the measurement executed the plurality of times, characterized in that the control arithmetic unit includes an average moisture content calculation unit configured to calculate an average moisture content by averaging measured moisture content in the measurement executed the plurality of times, and wherein the control arithmetic unit includes a state diagnosis unit configured to evaluate the presence or absence of an abnormality in the mass measurement unit by comparing the average moisture content with the theoretical moisture content of the standard substance stored in the storage unit, and wherein the control arithmetic unit is further configured to evaluate an influence of an installation environment by determining whether the standard deviation is not more than a predetermined value.