A vaporization heat loss measuring apparatus measures humidity and a temperature of an atmosphere of a surrounding environment using an environmental humidity measuring part and an environmental temperature measuring part. Further, the apparatus measures humidity and a temperature of an atmosphere near a surface of a measuring object using an object humidity measuring part and an object temperature measuring part. Further, the apparatus calculates a vaporization heat loss from the surface of the measuring object using the environmental humidity, the environmental temperature, the object humidity, and the object temperature. Furthermore, the apparatus calculates a non-evaporative heat loss based on a measurement result of a heat flow measuring part, and calculates a metabolic expenditure using the vaporization heat loss and the non-evaporative heat loss.
