Abstract: The present invention relates to an ozone sterilization device and method for sterilizing source water of water supply drainage using ozone generated in an ozone generator. The method includes a first process in which source water inputted to a first water block is sucked and discharged; a second process in which source water is sprayed onto ozone through the first ejector, wherein the above routine is repeatedly performed for thereby generating ozone water; a third process in which the ozone water which source water and ozone is mixed is discharged to the discharge unit separated by the first water block, and the ozone not dissolved is collected by a first gas staying tank; and a fourth process in which the source water of the inlet unit is sucked and passed through a second ejector, and the ozone from the first gas staying tank is sucked by a second vacuum pipe.