Abstract: There is provided a technique that includes: a first gas supply line configured to supply a first gas to a substrate in a process chamber; a first exhaust line connected to a first pump and exhausting the first gas supplied to the substrate; a first valve installed at the first exhaust line; a second gas supply line configured to supply a second gas to the substrate in the process chamber; a second exhaust line connected to a second pump and exhausting the second gas supplied to the substrate; a second valve installed at the second exhaust line; and a controller capable of controlling the first valve and the second valve, so as to perform a first line change processing of exhausting the first gas supplied to the substrate toward the second pump via the second exhaust line, when determining that the first exhaust line transitioned into a predetermined state.