PURPOSE: To regulate a quality of the air corresponding to fungi generating initial and growing/propagating environmental conditions without using chemicals.

CONSTITUTION: The method for preventing generation and propagation of fungi comprises the steps of (S1) sensing gas such as hydrocarbon, etc., relative to temperature, humidity and fungi generation and propagation, (S2) correcting sensed output of gas according to sensed temperature and humidity, (S3) calculating to decide fungi generating/propagating states based on the corrected gas sensing output, sensed temperature and humidity, relative data of the gas and the temperature, the humidity regarding the previously stored fungi generating and propagating environment, (S4) outputting a control temperature for so altering quality of the air such as temperature/humidity as to suppress fungi generation and propagation based on the calculated and decided results, and (S5) operating its air quality controller.