In the present invention, a gas pipe integrated block has a plurality of internal pipe paths. The plurality of internal pipe paths are connected to an ozone generator, control means, a raw gas supply port, an ozone gas output port, and cooling water inlet/outlet ports, to thereby form a unit in which a raw gas input pipe path and an ozone gas output pipe path are integrated. The raw gas input pipe path extends from the raw gas supply port through an automatic pressure controller to the ozone generator. The ozone gas output pipe path extends from the ozone generator through a gas filter, an ozone concentration meter, and a flow rate controller, to the ozone gas output port.