The present invention provides a method and an apparatus for condensing ozone arranged so as to efficiently take out the ozone gas of a predetermined concentration, although its construction is simple. The method for condensing the ozone gas comprises acting ozone-oxygen mixture gas on an adsorbing cylinder which is filled in its interior area with an adsorbent so as to selectively adsorb the ozone gas to an adsorbent and desorbing the selectively adsorbed ozone gas so as to condense and purify the ozone gas. The method further includes acting the ozone-oxygen mixture gas on the adsorbent in non-cooled state to selectively adsorb the ozone gas to the adsorbent and vacuuming the adsorbing cylinder on performing desorption-operation of the ozone gas to desorb the ozone gas from the adsorbent.