Résumé dans la langue de publication, traduction non disponible A cleaning agent characterized in that the agent comprises 0.1 to 4 wt.% of hydrofluoric acid, a surfactant of the following formula (1) in a concentration of 50 to 1500 ppm or a surfactant of the following formula (2) or (3) in a concentration of 50 to 100000 ppm, and the balance water, and a cleaning method of the surfaces of silicon wafers and the like using the agent RfCOONH4 wherein Rf is a fluorine-containing hydrocarbon group having 5 to 9 carbon atoms Rf'O(CH2 CH2 O)nR Rf'(CH2 CH2 O)nR wherein Rf' is a fluorine-containing hydrocarbon group having 5 to 15 carbon atoms, R is hydrogen or alkyl having 1 to 4 carbon atoms, and n is 5 to 20.