An ozone supplying apparatus according to an embodiment of the present invention is an ozone gas supplying apparatus which supplies an ozone gas to a vacuum apparatus. The ozone supplying apparatus includes an ozone generator configured to generate the ozone gas, a first flow controller configured to control a flow rate of the ozone gas generated by the ozone generator, a second flow controller configured to control a flow rate of the ozone gas supplied to the vacuum apparatus, and a main pipe provided on a secondary side of the first flow controller and on a primary side of the second flow controller, with the ozone gas being introduced into the main pipe at such a flow rate that an internal pressure of the main pipe is controlled to be lower than atmospheric pressure by the first flow controller.