PURPOSE: To provide a method for impregnating fluid or solid impregnant to an article such as an electronic component without using a pressure-resistant vessel, a vacuum unit, a pressurizing unit, etc., which is indispensable in the case of applying a method for impregnating.

CONSTITUTION: A method for impregnating liquid or solid impregnant by a temperature cycling comprises the steps of preheating an article to a temperature t2 by using a normal vessel to be used at the atmospheric pressure, and alternately setting a highest temperature t1 in which the impregnant does not lose its fundamental physical properties as the impregnant and an optimum impregnating temperature tw of the impregnant for a predetermined time in contact at predetermined times in the cycle.