A cleansing apparatus comprising: a table 3 for supporting a semiconductor substrate 30 horizontally; a high frequency solution injector 20 capable of injecting a solution to the upper surface 30a and the side surface 30c of the semiconductor substrate 30 supported by the table 3 with the application of vibration at high frequency; a cover 2 capable of tightly enclosing the semiconductor substrate 30 supported by the table 3; and pressure reducing means 18 for reducing the pressure in a space, in which the semiconductor substrate 30 is enclosed with the cover 2. The semiconductor substrate can be cleansed efficiently at a low cost and kept in clean state after the cleansing until it is dried.