A temperature adjuster (20) is configured to adjust temperature associated with a first gas supplying medium (10) for providing first gas to be mixed. A first flow rate controller (30) is configured to control a flow rate of the first gas. A second flow rate controller (40) is configured to control a flow rate of second gas to be mixed that is different from the first gas. A mixer (50) is configured to supply mixed gas in which the first gas supplied by the first flow rate controller (30) and the second gas supplied by the second flow rate controller (40) have been mixed.
