Abstract: A first on-off valve (2) and a second on-off valve (3) each are a two-port valve. A first passage block (5) is provided with a first on-off valve-corresponding inflow passage (11) and a first on-off valve-corresponding outflow passage (12). A second passage block (6) is provided with a second on-off valve-corresponding inflow passage (14) and a second on-off valve-corresponding outflow passage (15). The second on-off valve-corresponding outflow passage (15) is in communication with an upstream side portion of the first on-off valve-corresponding outflow passage (12) via a communicating passage (13) formed in the first passage block (5). An orifice (20) is provided between the second on-off valve-corresponding outflow passage (15) and the communicating passage (13).