To provide a method for efficiently recovering ozone gas from ozone water and a method for effectively utilizing the recovered ozone gas.

The ozone gas recovery method uses a packed tower having at least two packed beds partitioned by gas backflow prevention plates and comprises introducing ozone water from the upper side and a purge gas from the lower side into the tower and bringing the ozone water into countercurrent contact with the ozone gas to transfer/recover ozone into the gas phase. The method for reusing ozone comprises introducing the recovered ozone gas into an absorption tower of a packed tower type. The ozone water may be waste ozone water after an ozone treatment. Thus, clean ozone gas can be efficiently recovered from ozone water. Since the recovered ozone gas has good characteristics, it can be used for many applications. The efficiency of using ozone is improved and the equipment or load for treating waste ozone water can be reduced.