In a cleaning treatment of a substrate using an aqueous solution of ammonium fluoride or a mixture of an aqueous solution of ammonium fluoride and hydrofluoric acid as a cleaning liquid, the cleaning liquid is replenished by at least one liquid selected from the group consisting of water, ammonia, aqueous ammonia, and an aqueous solution of ammonium fluoride with the lapse of time during the use of the cleaning liquid, in which the required amount of the liquid to be added according to the time lapse is calculated based on the measurement date and controlled, or the component concentration of the cleaning liquid is detected and the liquid is added according to the obtained result, so that not only can the substrate be cleaned uniformly and stably, but also a resource saving and a reduction in waste can be achieved.