A method for decontaminating a low-temperature article, the method comprising: an applying step including applying a decontamination agent to external surfaces of a low-temperature article and supplying a mist of decontamination agent to a first external surface of said low-temperature article to form a condensed film of the decontamination agent on said first external surface; and a drying step including ultrasonically vibrating vibration boards disposed on a periphery of the low-temperature article to generate sound flows from board surfaces by an ultrasound in a vertical direction, irradiating with ultrasonic waves the low-temperature article with the decontamination agent applied thereto, subjecting said first external surface of the low-temperature article to ultrasonic vibration and acoustic radiation pressure, supplying dry air to the first external surface and drying said first external surface.