A substrate-processing apparatus includes a sample table which mounts thereon a to-be-processed substrate, a first line which supplies a chemical solution, a second line which supplies a cleaning liquid, a three-way valve connected to the first and second lines and configured to select one of the first and second lines, a filter provided across the first line upstream of the three-way valve, and configured to eliminate a foreign material from the chemical solution, and a nozzle provided downstream of the three-way valve and configured to discharge the chemical solution or the cleaning liquid when the first or second line is selected via the three-way valve. The three-way valve selects the first line when the substrate is coated with the chemical solution, and selects the second line in other cases.