[Problem] To provide a moisture meter which can detect a heat-illness risk-index early and which is effective as an assistance means in which a subject can carry out a proper moisture adjustment. [Solving Means] A moisture meter including: a moisture measurement unit 30 which is held by an armpit R of a subject M and which measures the amount of moisture of the subject M by being in contact with a skin surface V of the armpit R, a sensor unit 27 for measuring the temperature and humidity of the environment of the subject M, and a processing unit 44 which obtains the amount of moisture of the subject from the moisture measurement unit 30, which sets a Wet-Bulb Globe temperature (WBGT) value from the relation between the temperature and humidity from the sensor unit 27 and which obtains the heat-illness risk-index by referring to a relation table 200 between the amount of moisture of the subject M and the Wet-Bulb Globe temperature (WBGT) value.
