Abstract: In a cleaning method, two kinds of cleaning solutions, one of which is acid solution of about pH 2 or less (first cleaning solution) and other of which is acid solution of about pH 3 to 4 (second cleaning solution), are successively used to clean a semiconductor substrate. In a first cleaning step, the semiconductor substrate is cleaned with the first cleaning solution to transform metals on the surface of the semiconductor substrate to metallic complex salts, and then in a second cleaning step the semiconductor substrate is cleaned with the second cleaning solution to transfer the metallic complex salts adsorbed on the surface of the semiconductor substrate into the second cleaning solution by osmotic pressure due to the difference in pH between the first and second cleaning solutions.