A pump portion for taking in and discharging solutions includes a first plunger pump with a small capacity and a second plunger pump with a large capacity. Intake ports of both the plunger pumps are connected in parallel to a common port of a switching valve with a first three-way valve interposed therebetween. The first three-way valve connects the intake port of one of the plunger pumps to the switching valve. Discharge ports of both the plunger pumps are connected in parallel to one port of the switching valve with a second three-way valve interposed therebetween. The second three-way valve connects the discharge port of one of the plunger pumps to the switching valve.