PURPOSE: To effectively remove an organic material adhered on a semiconductor wafer, by irradiating the semiconductor wafer with far ultraviolet radiation after vapor washing and drying the semiconductor wafer and before taking it out of the unit.

CONSTITUTION: In order to remove an organic material adhered on a wafer 10, supply of N2 gas is stopped after the wafer 19 is predried. Then, gas (air) containing filtered oxygen is supplied into a wafer take-out section 4 through second supply ducts 33a and 33b. At the same time with the supply of air, the wafer 19 is irradiated with far ultraviolet radiation. The internal atmosphere within the section 4 is thereby ozonized and/or converted to radical oxygen, whereby any organic material adhered on the wafer 19 such as carbon is decomposed by the ozon/radical oxygen and the far ultraviolet radiation. In this manner, the organic material can be removed completely from the surface of the wafer 19.