Dew formation prediction method and apparatus, environment air temperature estimating method and apparatus and recording and/or reproducing apparatus

A dew formation occurrence detection apparatus for detecting the dew formation on a drum 4 of a tape transport system provided on the electronic equipment 1 as an object for measurement. The dew formation occurrence detection apparatus includes a drum temperature detection unit 8 for detecting the temperature of the drum 4, an environment air temperature acquisition unit 6 for acquiring the environment air temperature of the electrical equipment 1 and a dew point temperature calculating unit 6 for calculating, from this environment air temperature, the dew point temperature at the humidity which takes the operating environment of the electronic equipment 1 into account. When the temperature of the drum 4 is not higher than this dew point temperature, it is verified that dew formation has occurred.